View source for .us

{{short description|Internet country code top-level domain for the U.S.}}
{{Use American English|date=July 2018}}
{{Use mdy dates|date = July 2018}}
{{Infobox top level domain
| name = us
| image = DotUS domain logo.png
| introduced = {{start date and age|1985|2|15}}
| type = [[Country code top-level domain]]
| status = Active
| registry = [[GoDaddy#GoDaddy_Registry|Registry Services, LLC]] (owned by [[GoDaddy]])
| sponsor = [[National Telecommunications and Information Administration]]
| intendeduse = Entities connected with the [[United States]]
| actualuse = Used in the United States but not as widely as [[Generic top-level domain|gTLDs]] <br>
{{bulleted list|1=U.S. state, tribal, and local governments (declining in favor of [[.gov]])|2=Some American businesses as alternative to [[.com]]|3=[[Domain hack]]s (e.g. [[del.icio.us]])
}}
| registereddomains = 2,053,374
| dateregistereddomains = December 2023
| refregistereddomains = <ref>{{cite web |title=.US Top-Level Domain Stats and Trends |website=.US Domains - About.US |language=en |date=2023 |publisher=Registry Services, LLC |publication-place=Tempe, Arizona |url=https://www.about.us/doc/resources/ebooks/202312_US_Monthly_Report_DEC23_FNL.pdf |access-date=2024-10-28}}</ref>
| restrictions = Connection with the U.S. requirement can be enforced by challenge but rarely is
| structure = 2nd-level registrations allowed; originally only 3rd- or 4th-level registrations in a complex hierarchy
| document = RFC 1480; [https://www.ntia.doc.gov/page/2011/us-domain-space USDoC agreements with Neustar]; [https://www.about.us/policies Other policies]
| disputepolicy = [https://www.ntia.doc.gov/files/ntia/publications/ustld2007_33_appg_usdrp.pdf usTLD Dispute Resolution Policy (usDRP)]
| website = {{URL|https://www.about.us/|about.us}}
| dnssec = Yes
}}

'''us''' is the [[Internet]] [[country code top-level domain]] (ccTLD) for the [[United States]]. It was established in February 1985. Registrants of us domains must be U.S. citizens, residents, or organizations – or foreign entities with a presence in the United States or a territory of the United States.<ref>{{Cite web|url=https://www.about.us/policies/ustld-nexus-requirements|title=UsTLD Nexus Requirements Policy for Registrants&#124; About.US - About.US|access-date=December 3, 2020|archive-date=April 15, 2021|archive-url=https://web.archive.org/web/20210415075816/https://www.about.us/policies/ustld-nexus-requirements|url-status=dead}}</ref> Most registrants in the U.S. have registered for [[.com]], [[.net]], [[.org]] and other [[generic top-level domain|gTLD]]s, instead of ''us'', which has primarily been used by state and local governments, even though private entities may also register ''us'' domains.<ref>{{Cite web|last=|first=|date=|title=zoom.us (video call app)|url=https://zoom.us/|url-status=live|archive-url=https://web.archive.org/web/20020606091959/http://www.zoom.us:80/ |archive-date=June 6, 2002 |access-date=2021-01-07|website=Zoom Video|language=en-US}}</ref> The domain is managed by [[GoDaddy#GoDaddy_Registry|Registry Services, LLC]], an acquired subsidiary domain name registry of [[GoDaddy]], on behalf of the [[United States Department of Commerce]].<ref>{{Cite web |title=About the .US Top-Level Domain - Overview {{!}} .US Domains - About.US |url=https://www.about.us/aboutus |access-date=2023-12-05 |website=www.about.us}}</ref>

Domain ''us'' is less commonly used by American businesses and enterprises than the internationally more common ''com''.<ref>{{Cite web |date=2022-10-17 |title=The Most Popular Domain Extensions {{!}} Top 10 TLDs |url=https://www.ionos.co.uk/digitalguide/domains/domain-extensions/most-popular-domain-extensions/ |url-status=live |archive-url=https://web.archive.org/web/20230510164252/https://www.ionos.co.uk/digitalguide/domains/domain-extensions/most-popular-domain-extensions/ |archive-date=2023-05-10 |access-date=2023-05-10 |website=[[Ionos]]}}</ref>

==History==
On February 15, 1985, ''us'' was created as the Internet's first ccTLD.<ref>{{cite web|title=History of the Internet. ccTLDs in chronological order of Top Level Domain creation at the Internic.|first=Elisabeth|last=Portenueve|publisher=[[Association française pour le nommage Internet en coopération|AFNIC]]|date=October 23, 2003|access-date=March 29, 2015|url=http://www.ccwhois.org/ccwhois/cctld/ccTLDs-by-date.html|archive-url=https://web.archive.org/web/20011012191130/http://www.ccwhois.org/ccwhois/cctld/ccTLDs-by-date.html|url-status=dead|archive-date=October 12, 2001}}</ref><ref>{{Cite web|url=https://www.iana.org/domains/root/db/us.html|title=IANA—.us Domain Delegation Data|website=www.iana.org|access-date=2020-02-01}}</ref> Its original administrator was [[Jon Postel]] of the [[Information Sciences Institute]] (ISI) at the [[University of Southern California]] (USC). He administered ''us'' under a subcontract that the ISI and USC had from [[SRI International]] (which held the ''us'' and the gTLD contract with the [[United States Department of Defense]]) and later [[Network Solutions]] (which held the ''us'' and the gTLD contract with the [[National Science Foundation]]).

Postel and his colleague Ann Westine Cooper<ref>{{cite web|url=https://public.resource.org/eti/RoundThree01.html|title=Exploring the Internet: Round Three, Marina del Rey|author=Carl Malamud|date=1992|website=public.resource.org|access-date=19 October 2018<!-- https://public.resource.org/eti/Preface.html https://public.resource.org/eti/index.html -->}}</ref> codified the ''us'' ccTLD's policies in December 1992 as RFC 1386<ref>{{cite journal|url=https://tools.ietf.org/html/rfc1386|title=The US Domain|first1=Postel|last1=Jon|first2=Cooper|last2=Ann Westine|website=tools.ietf.org|date=December 1992 |access-date=19 October 2018}}</ref> and revised them the following June in RFC 1480. Registrants could only register third-level domains or higher in a geographic and organizational hierarchy. From June 1993 to June 1997, Postel delegated the vast majority of the geographic subdomains under ''us'' to various public and private entities. ''us'' registrants could register with the delegated manager for the specific zone they wished to register in, but not directly with the ''us'' administrator. In July 1997, Postel instituted a "50/500 rule" that limited each delegated manager to 500 localities maximum, 50 in a given state.<ref name="Neustar compliance 2013" />

In June 1998, Postel raised the possibility of covering [[Internet Assigned Numbers Authority|IANA]] operating costs by charging locality name registrars, who would pass the costs along to individual registrants. In September 1998, the [[United States Postal Service]] proposed funding the operations in order to assume control of ''us'', as part of a plan to diversify away from postage revenue.{{sfn|Wass|2003|p=127}} On October 1, 1998, the NSF transferred oversight of the ''us'' domain to the [[National Telecommunications and Information Administration]] (NTIA) of the [[United States Department of Commerce]].<ref>[https://www.ntia.doc.gov/federal-register-notice/2000/requesting-comments-draft-statement-work-regarding-us Requesting comments on draft statement of work regarding ''us'' ]</ref> Postel died that month, leaving his domain administration responsibilities with ISI. In December 2000, these responsibilities were transferred to Network Solutions, which had recently been acquired by [[Verisign]].<ref name="Neustar compliance 2013" /><ref>[https://www.ntia.doc.gov/page/amendment-21-nsi-cooperative-agreement Amendment 21 to the NSI Cooperative Agreement]</ref><ref>[https://eprints.qut.edu.au/15901/1/Elizabeth_Williams_Thesis.pdf THE GLOBALISATION OF REGULATION AND ITS IMPACT ON THE DOMAIN NAME SYSTEM : DOMAIN NAMES AND A NEW REGULATORY ECONOMY by ELIZABETH A WILLIAMS]</ref>

On October 26, 2001, [[Neustar]] was awarded the contract to administer ''us''. On April 24, 2002, second-level domains under ''us'' became available for registration. One of the first ''us'' [[domain hack]]s, icio.us, was registered on May 3, 2002, for the creation of the subdomain [[Delicious (website)|del.icio.us]].<ref>[[Whois]] query for the domain names "DELICIO.US" and "ICIO.US". Whois database last updated March 29, 2015. Accessed March 29, 2015.</ref><ref>{{cite web|title=A Del.icio.us Interview|first=Michael|last=Lopp|author-link=Rands|work=Rands in Repose|date=December 3, 2004|access-date=March 29, 2015|url=http://randsinrepose.com/archives/a-delicious-int/}}</ref> A moratorium was placed on additional delegations of locality-based namespaces, and Neustar became the default delegate for undelegated localities.<ref>Manheim, Karl M. and Solum, Lawrence B., [https://digital.sandiego.edu/cgi/viewcontent.cgi?article=1009&context=lwps_econ "An Economic Analysis of Domain Name Policy"] (2004). University of San Diego Law and Economics Research Paper Series. 1. http://digital.sandiego.edu/lwps_econ/art1</ref> Neustar's contract was renewed by the [[National Telecommunications and Information Administration]] (NTIA) in 2007 and most recently in 2014.<ref name="Neustar compliance 2013" /><ref>{{cite web|title=.us Domain Space|publisher=[[National Telecommunications and Information Administration]]|date=February 17, 2015|access-date=March 28, 2015|url=http://www.ntia.doc.gov/page/2011/us-domain-space}}</ref>

On March 31, 2019, the ''us'' registry made it clear that under its Acceptable Use Policy it would not allow the sale of opioids through the ''us'' top level domain.<ref>{{Cite web|url=https://www.about.us/blog/tackling-the-opioid-crisis-by-cutting-off-online-sales-in-the-ustld|title=Tackling the Opioid Crisis by Cutting off Online Sales in the usTLD - About.US}}</ref>

In Q2 2020, [[GoDaddy]] acquired Neustar's registry business.<ref>{{Cite press release |last= |first= |title=GoDaddy Acquires Neustar's Registry Business |url=https://www.prnewswire.com/news-releases/godaddy-acquires-neustars-registry-business-301036134.html |access-date=2023-10-26 |website=www.prnewswire.com |language=en}}</ref>

== Locality namespace ==
The ''us'' ccTLD is historically organized under a complex ''locality namespace'' hierarchy. Until second-level registrations were introduced in 2002, ''us'' permitted only fourth-level domain registrations of the form {{var|organization-name}}.{{var|locality}}.{{var|state}}.us, with some exceptions for government entities. Registrants of locality-based domains must meet the same criteria as in the rest of the ''us'' ccTLD. Though the locality namespace is most commonly used for government entities, it is also open to registrations by private businesses and individuals. Since 2002, second-level domain registrations have eclipsed those in the locality namespace, and many local governments have transitioned to [[.org]] and other TLDs.<ref name="Neustar compliance 2013" /> In the 2010s, the first [[List of Internet top-level domains#North America|top-level domains for U.S. cities]] became available as paid alternatives to third-level locality domains, including [[.nyc]] as an alternative to .new-york.ny.us.

Many locality-based zones of ''us'' are delegated to various public and private entities known as ''delegated managers''. Domains in these zones are registered through the delegated manager, rather than through GoDaddy. As the delegated managers are expected to receive requests directly from registrants, few if any [[domain name registrar]]s serve this space, possibly contributing to its lower visibility and utilization. RFC 1480 describes the rationale for the locality namespace's deep hierarchy and local delegation:<ref name="Neustar compliance 2013" />

{{blockquote|One concern is that things will continue to grow dramatically, and this will require more subdivision of the domain name management. Maybe the plan for the US Domain is overkill on growth planning, but there has never been overplanning for growth yet.}}

This hierarchical system has proven unappealing to companies that operate nationally or globally.{{sfn|Wass|2003|pp=127–129}}

As of October 31, 2013, 12,979 domains were registered under the locality namespace, of which 3,653 were managed by about 1,300 delegated managers while 9,326 were managed by Neustar as the ''de facto'' manager.<ref name="Neustar structure">{{cite web|title=Structure and History|publisher=Neustar|access-date=March 28, 2015|url=http://www.neustar.us/ustld-stakeholder-council/structure-and-history/|archive-date=April 2, 2015|archive-url=https://web.archive.org/web/20150402142158/http://www.neustar.us/ustld-stakeholder-council/structure-and-history/|url-status=dead}}</ref> According to a 2013 survey of 539 delegated managers, 282 were state or local government agencies, while 98 were private individuals and 85 were commercial [[Internet service provider]]s. Nearly 90% of the respondents offer domain registrations for free.<ref name="Neustar compliance 2013" />

The [[.au]] and [[.ca]] ccTLDs have also established third- and fourth-level locality namespaces, though the .ca locality namespace is no longer open to registrations. The [[.cn]] ccTLD maintains a third-level locality namespace in general use.

===States and territories {{anchor|Second-level domains for states}}===
A two-letter [[second-level domain]] is formally reserved for each [[U.S. state]], federal territory, and the [[District of Columbia]]. Each domain corresponds to a [[List of U.S. state abbreviations|USPS abbreviation]]. For example, .ny.us is reserved for websites affiliated with [[New York (state)|New York]], while .va.us is for those affiliated with [[Virginia]]. Second-level domains are also reserved for five U.S. territories: .as.us for [[American Samoa]], .gu.us for [[Guam]], .mp.us for the [[Northern Mariana Islands]], .pr.us for [[Puerto Rico]], and .vi.us for the [[United States Virgin Islands|U.S. Virgin Islands]]. However, these domains go unused because each territory has its own ccTLD per [[ISO 3166-1 alpha-2]]: respectively, [[.as]], [[.gu]], [[.mp]], [[.pr]], and [[.vi]].

[[File:Pennsylvanian license plate, 2000.jpg|thumb|right|[[Vehicle registration plates of Pennsylvania]] bore the URL {{URL|WWW.STATE.PA.US}} from September 1999 to December 2004.]]

A state's main government portal is usually found at the third-level domain state.{{var|state}}.us, which is reserved for this purpose. However, some state administrations prefer [[.gov]] domains: for example, [[California]]'s government portal is located at {{URL|http://www.ca.gov/}}. Other than for state governments, no third-level domain registrations are permitted under state or territory second-level domains.

A few additional names are reserved at the second level for government agencies that are not subordinate to a state government:

* ''fed.us'' for agencies of the U.S. federal government (historically rarely used; in practice superseded by ''.gov'')
** Example: {{URL|http://www.fs.fed.us/}} (formerly the [[United States Forest Service]])
* ''isa.us'' for interstate authorities created by [[interstate compact]]s
** Example: {{URL|http://imcc.isa.us/}} (Interstate Mining Compact Commission)
* ''nsn.us'' for [[List of federally recognized tribes|Native Sovereign Nation]]s (which may also use ''-nsn.gov'')
** Example: {{URL|https://www.mohegan.nsn.us/}} ([[Mohegan Tribe]])
* ''dni.us'' for distributed national institutes
** Example: {{URL|http://ccj.ncsc.dni.us/}} (formerly the [[Conference of Chief Justices]], part of the [[National Center for State Courts]])

===Locality domains===
A large number of third-level domains are reserved for localities within states. Each fourth-level domain registration under this namespace follows the format {{var|organization-name}}.{{var|locality}}.{{var|state}}.us, where {{var|state}} is a state's two-letter postal abbreviation and {{var|locality}} is a hyphenated name that corresponds to a [[ZIP code]] or appears in a well-known atlas.<ref name="Neustar compliance 2013">{{cite web|title=..US Compliance Report|publisher=Neustar|date=n.d.|access-date=November 21, 2017|url=https://ns-cdn.neustar.biz/creative_services/biz/neustar/www/resources/domain-names/us-locality-compliance-report.pdf}}</ref> Some delegated managers alternatively register domains under common abbreviations of locality names, such as:

* chi.il.us for [[Chicago]] (until 1997)<ref>{{cite web|title=The Clout Project, what is it, and how do I use it?|first=Steve|last=Piette|publisher=The Clout Project|location=Chicago|date=May 12, 2013|accessdate=June 9, 2025|url=http://www.chicago.il.us/project.html}}</ref>
* la.ca.us for [[Los Angeles]]
* nyc.ny.us for [[New York City]]
* sf.ca.us for [[San Francisco]]
* sj.ca.us for [[San Jose, California]]
* slc.ut.ca for [[Salt Lake City]]

Two values of {{var|organization-name}} are formally reserved across the entire locality namespace for city and county governments:<ref name="Neustar compliance 2013" />

* ci.{{var|locality}}.{{var|state}}.us for city governments
** Example: {{URL|https://www.ci.east-palo-alto.ca.us/}} ([[East Palo Alto, California]]), {{URL|https://ci.mansfield.oh.us/}} ([[Mansfield, Ohio]])
* co.{{var|locality}}.{{var|state}}.us for county governments
** Example: {{URL|https://www.co.adams.id.us/}} ([[Adams County, Idaho]])

Delegated managers often reserve additional names for different kinds of local governments:<ref name="Neustar compliance 2013" />

* ''borough''.{{var|locality}}.{{var|state}}.us for [[Borough (United States)|borough]] governments
** Example: {{URL|https://borough.shippensburg.pa.us/}} ([[Shippensburg, Pennsylvania]])
* ''city''.{{var|locality}}.{{var|state}}.us for city governments
** Example: {{URL|https://www.city.waltham.ma.us/}} ([[Waltham, Massachusetts]])
* ''county''.{{var|locality}}.{{var|state}}.us for county governments
* ''parish''.{{var|locality}}.{{var|state}}.us for [[List of parishes in Louisiana|parish]] governments (unused)
* ''town''.{{var|locality}}.{{var|state}}.us for town governments
** Example: {{URL|https://www.town.northlake.tx.us/}} ([[Northlake, Texas]]), {{URL|https://www.town.windermere.fl.us/}} ([[Windermere, Florida]])
* ''twp''.{{var|locality}}.{{var|state}}.us or ''township''.{{var|locality}}.{{var|state}}.us for [[Township (United States)|township]] governments
** Examples: {{URL|https://twp.jerusalem.oh.us/}} ([[Jerusalem Township, Lucas County, Ohio]]), {{URL|https://www.township.wilson.mn.us/}} ([[Wilson Township, Winona County, Minnesota]])
* ''vil''.{{var|locality}}.{{var|state}}.us or ''village''.{{var|locality}}.{{var|state}}.us for village governments
** Examples: {{URL|https://www.vil.bellwood.il.us/}} ([[Bellwood, Illinois]]), {{URL|https://www.village.fairport.ny.us/}} ([[Fairport, New York]])

In some cases, a local government that serves as the delegated manager for its own locality may locate its website directly under the {{var|locality}}, omitting the {{var|organization-name}}. For example, the website of the City of [[Brunswick, Ohio]], is located at {{URL|https://www.brunswick.oh.us/}} rather than www.ci.brunswick.oh.us, and the website of [[Delhi Township, Ohio]], is located at {{URL|https://www.delhi.oh.us/}} instead of www.twp.delhi.oh.us. Unusually, [[Lima, Ohio]], is located at {{URL|http://www.cityhall.lima.oh.us/}}.

Many large cities use [[.gov]] extensions, for example [[Chicago]] ({{URL|https://www.chicago.gov/}}); [[Rochester, New York]] ({{URL|https://www.cityofrochester.gov/}}); and Atlanta ({{URL|https://www.atlantaga.gov/}}). Although most [[New York City]] websites have moved to {{URL|https://www.nyc.gov/}}, ''us'' redirects exist for individual city agencies, such as the [[New York City Independent Budget Office|Independent Budget Office]] at {{URL|https://www.ibo.nyc.ny.us/}} and the [[New York City Board of Elections|Board of Elections]] at {{URL|http://vote.nyc.ny.us/}}.

Private organizations and individuals may register fourth-level domains parallel to these government domains, for example:

* {{URL|https://bcn.boulder.co.us/}} (a [[community network]] in [[Boulder, Colorado]])
* {{URL|https://hpnc.cincinnati.oh.us/}} (the [[neighborhood council]] for [[Hyde Park, Cincinnati]])
* {{URL|https://michael.silverton.palo-alto.ca.us/}} ([[Michael Silverton]], a resident of [[Palo Alto, California]])
* {{URL|https://owen.sj.ca.us/}} or {{URL|http://owen.san-jose.ca.us/}} (a family in [[San Jose, California]])<ref>{{cite news|title=Registering in the US Domain (For Free)|first=R.K.|last=Owen|work=[[Linux Journal]]|issue=39|date=July 1997|issn=1075-3583|url=https://www.linuxjournal.com/article/2011}}<!-- https://web.archive.org/web/20201217100817/http://owen.sj.ca.us/~rk/howto/usdomain.html --></ref>
* {{URL|https://www.sna.providence.ri.us/}} (the [[neighborhood association]] for [[Hope, Providence, Rhode Island]])
* {{URL|https://social.seattle.wa.us/}} (a [[Mastodon (social_network)|Mastodon]] instance in [[Seattle]])
* {{URL|https://social.tulsa.ok.us/}} (a Mastodon instance in [[Tulsa, Oklahoma]])
* {{URL|https://wclug.chicago.il.us/}} (a [[Linux user group]] in [[Chicago]])
* {{URL|http://well.sf.ca.us/}} ([[The WELL]], a [[virtual community]] in [[San Francisco]])

===Affinity namespaces===
Directly beneath the {{var|state}}.us zone, several ''affinity namespaces'' are reserved for specific purposes:

* ''state'': state government agencies ({{var|organization-name}}.state.{{var|state}}.us)
** Examples: {{URL|https://arkleg.state.ar.us/}} ([[Arkansas General Assembly]]), {{URL|https://mdhhsmiimmsportal.state.mi.us/}} ([[Michigan Department of Health and Human Services]] immunization records portal), {{URL|https://tap.state.nm.us/}} ([[New Mexico Taxation and Revenue Department]] tax filing system)
* ''dst'': government agencies in [[Special district (United States)|administrative district]]s ({{var|organization-name}}.dst.{{var|state}}.us)
** Example: {{URL|https://lnva.dst.tx.us/}} ([[Lower Neches Valley Authority]])
* ''cog'': [[Council of governments|councils of governments]], that is, federations of cities or counties ({{var|organization-name}}.cog.{{var|state}}.us)
** Example: {{URL|https://stdc.cog.tx.us/}} ([[South Texas Development Council]])
* ''k12'': public elementary and/or secondary unified school districts ({{var|district-name}}.k12.{{var|state}}.us) individual schools ({{var|school-name}}.k12.{{var|state}}.us). Also used by public agencies overseeing educational institutions.
** Examples: {{URL|https://iberia.k12.la.us/}} ([[Iberia Parish School District]]), {{URL|https://www.pctc.k12.oh.us/}} ([[Pioneer Career and Technology Center]]), {{URL|https://ospi.k12.wa.us/}} ([[Washington State Office of Superintendent of Public Instruction]])
** ''pvt.k12'': private elementary or secondary schools ({{var|school-name}}.pvt.k12.{{var|state}}.us or {{var|school-name}}.{{var|diocese-name}}.pvt.k12.{{var|state}}.us)
*** Examples: {{URL|https://www.ionaprep.pvt.k12.ny.us/}} ([[Iona Preparatory School]]), {{URL|https://www.stmary-wooster.cld.pvt.k12.oh.us/}} (a private K-12 school in the [[Roman Catholic Diocese of Cleveland]] in Ohio)
** The ''k12.ma.us'' delegate manager additionally delegates domains under ''chtr.k12.ma.us'' and ''paroch.k12.ma.us'' for [[Charter schools in the United States|charter school]]s and [[parochial school]]s, respectively.<ref>{{cite web|title=Public Suffix List|work=[[Public Suffix List]]|publisher=Mozilla Foundation|location=Mountain View, California|date=July 18, 2025|accessdate=July 20, 2025|url=https://publicsuffix.org/list/public_suffix_list.dat}}</ref>
* ''cc'': community colleges ({{var|school-name}}.cc.{{var|state}}.us)
** Example: {{URL|https://www.lakeland.cc.il.us/}} ([[Lake Land College]])
* ''tec'': technical and vocational schools ({{var|school-name}}.tec.{{var|state}}.us)
** Example: {{URL|https://ap.tec.pa.us/}} ([[Admiral Peary Vocational-Technical School]])
* ''lib'': public libraries ({{var|library-name}}.lib.{{var|state}}.us)
** Example: {{URL|https://www.monroecounty.lib.oh.us/}} ([[Monroe County District Library]])
* ''mus'': museums ({{var|museum-name}}.mus.{{var|state}}.us)
** Example: {{URL|http://www.ok-history.mus.ok.us/}} ([[Oklahoma Historical Society]])
* ''gen'': general independent entities (clubs or other groups not fitting into the above categories) ({{var|organization-name}}.gen.{{var|state}}.us)
** Examples: {{URL|https://www.mrc.gen.mn.us/}} (a amateur radio association in Minnesota), {{URL|https://luni.gen.il.us/}} (a [[Linux user group]] for northern Illinois), {{URL|https://squaredance.gen.or.us/}} (a statewide federation of [[square dance]] clubs)

Some of these affinity namespaces have been supplanted by more convenient [[sponsored top-level domain]]s. The first sTLD, [[.museum]], became available in October 2001 as an alternative to the .mus namespace. Since April 2003, the [[.edu]] top-level domain has been available as an alternative for community colleges, technical and vocational schools, and other tertiary educational institutions that might have previously used the .cc or .tec affinity namespaces.<ref>{{cite press release|title=EDUCAUSE Announces Expansion of Eligibility for .edu Internet Names to Nationally Accredited Institutions|publisher=[[Educause]]|date=February 11, 2003|access-date=August 28, 2016|url=http://net.educause.edu/edudomain/pr-eligibility.asp|archive-url=https://web.archive.org/web/20111204092109/http://net.educause.edu/edudomain/pr-eligibility.asp|archive-date=December 4, 2011|url-status=dead|df=mdy-all}}</ref>

Although the [[Kentucky Department of Education]] operates the .k12.ky.us namespace for [[List of school districts in Kentucky|Kentucky school districts]], most districts instead use subdomains of the less formal domain kyschools.us, which the department operates in a similar manner. For example, Gallatin county schools have a website at {{URL|http://www.gallatin.k12.ky.us/}}, while [[Paducah Public Schools]] are located at {{URL|http://paducah.kyschools.us/}} and the [[McCracken County Public Schools]] use {{URL|http://mccracken.kyschools.us/}} as a redirect to {{URL|http://www.mccrackencountyschools.net/}}.

==Kids.us==
The Dot Kids Implementation and Efficiency Act of 2002 ({{uspl|107|317}}) established a ''.kids.us'' [[second-level domain]]. The general public could register third-level domains under ''.kids.us'' for educational content that met strict requirements, including conformance to the [[Children's Online Privacy Protection Act]] and adherence to [[Children's Advertising Review Unit]] standards. Webpages were prohibited from linking outside the ''.kids.us'' namespace. On July 27, 2012, in response to declining usage and a petition by Neustar the previous year, the NTIA suspended ''.kids.us'' registrations. By that time, 651 domains were registered under ''.kids.us'', and only five registrants ([[Nickelodeon]], [[Nick Jr.]], [[PBS Kids]], the [[Smithsonian Institution|Smithsonian]] Center for Education and Museum Studies, and Super-Fun Sports Inc., operating trampoline.kids.us and trampolines.kids.us) were operating active websites.<ref>{{cite web|title=Kids.us Education Advisory Committee Report|publisher=Neustar|date=October 28, 2014|access-date=March 28, 2015|page=2|url=http://www.neustar.us/wp-content/uploads/2014/10/education-advisory-committee-final-report.pdf|archive-date=April 2, 2015|archive-url=https://web.archive.org/web/20150402092915/http://www.neustar.us/wp-content/uploads/2014/10/education-advisory-committee-final-report.pdf|url-status=dead}}</ref>

== Restrictions on use ==
Under ''us'' nexus requirements, ''us'' domains may be registered only by the following qualified entities:
* Any United States citizen or resident,
* Any United States entity, such as organizations or corporations,
* Any foreign entity or organization with a [[bona fide]] presence in the United States

To ensure that these requirements are met, [[GoDaddy]] frequently conducts "spot checks" on registrant information.

To prevent anonymous registrations that do not meet these requirements, in 2005 the [[National Telecommunications and Information Administration]] ruled that registrants of ''us'' domains may not secure private domain name registration via anonymizing proxies, and that their contact information must be made public.<ref>{{cite news
 | url=https://www.washingtonpost.com/wp-dyn/articles/A7251-2005Mar4.html
 | title=Ruling on '.us' Domain Raises Privacy Issues
 | work=washingtonpost.com
 | date=2005-03-04
 | access-date=2015-03-31 }}
</ref> Registrants are required to provide complete contact information without omissions.<ref>{{cite web |url=http://www.neustar.us/the-ustld-nexus-requirements/ |title=The usTLD Nexus Requirements Policy |publisher=neustar.us |date=2014-06-20 |access-date=2016-05-14 |archive-date=October 31, 2012 |archive-url=https://web.archive.org/web/20121031085221/http://www.neustar.us/the-ustld-nexus-requirements/ |url-status=dead }}</ref>

Under the locality namespace, delegated managers may impose additional requirements.<ref name="Neustar compliance 2013" /> For example, the former Texas Regional Hostmaster restricted each of its delegated localities to organizations that had a mailing address in that locality.<ref name="TXUS locality">{{cite web|title=Locality Domain Names in TX.US Administered by the Texas Regional Hostmaster|publisher=Texas Regional Hostmaster|date=May 4, 2000|access-date=March 29, 2015|url=http://www.ns.gen.tx.us/ftp/pub/requirements/locality.tx.us.names|archive-url=https://web.archive.org/web/20150308153625/http://www.ns.gen.tx.us/ftp/pub/requirements/locality.tx.us.names|archive-date=March 8, 2015|url-status=dead}}</ref>

== Other top-level domains related to the United States ==
Some [[sponsored top-level domain]]s (sTLDs) are restricted to U.S.-based entities, other than some grandfathered registrations. These domains are much more popular than the equivalent domains under ''us''.

{| class="wikitable"
!sTLD
!Allowed use
!us alternative
|-
|rowspan="2"|[[.edu|edu]]
|Community colleges
|cc.{{var|state}}.us
|-
|Technical and vocational schools
|tec.{{var|state}}.us
|-
|rowspan="4"|[[.gov|gov]]
|Federal government agencies
|fed.us
|-
|Tribal governments
|{{var|tribe}}.nsn.us
|-
|State governments
|state.{{var|state}}.us
|-
|Local governments
|{{var|type}}.{{var|locality}}.{{var|state}}.us
|-
|[[.mil|mil]]
|Armed forces
|{{n/a}}
|}

[[Territories of the United States]] use their own country code top-level domains (ccTLDs). Identical domains are reserved under ''us'' but in practice go unused.

{| class="wikitable"
!ccTLD
!Territory
!us alternative
|-
|[[.as|as]]
|{{Flag|American Samoa}}
|as.us
|-
|[[.gu|gu]]
|{{Flag|Guam}}
|gu.us
|-
|[[.mp|mp]]
|{{Flag|Northern Mariana Islands}}
|mp.us
|-
|[[.pr|pr]]
|{{Flag|Puerto Rico}}
|pr.us
|-
|[[.um|um]] (deprecated)
|{{Flag|United States Minor Outlying Islands}}
|um.us
|-
|[[.vi|vi]]
|{{Flag|United States Virgin Islands}}
|vi.us
|}

Some U.S. cities are the focus of [[generic top-level domain]]s under the [[New gTLD Program]]. These gTLDs are not necessarily affiliated with the delegated managers of the corresponding third-level domains within the ''us'' locality namespace.

{| class="wikitable"
!gTLD
!City
!us alternative
|-
|[[.boston|boston]]
|{{Flag|Boston}}
|boston.ma.us
|-
|[[.miami|miami]]
|{{Flag|Miami}}
|miami.fl.us
|-
|rowspan="2"|[[.nyc|nyc]]
|rowspan="2"|{{Flag|New York City}}
|new-york.ny.us
|-
|nyc.ny.us
|-
|[[.vegas|vegas]]
|{{Flag|Las Vegas}}
|las-vegas.nv.us
|}

Unofficially, some ccTLDs belonging to other countries are used by U.S.-based private organizations and state government agencies based on their similarity to [[List of U.S. state and territory abbreviations#Postal code|postal state abbreviation]]s or informal city name abbreviations.

{| class="wikitable"
!ccTLD
!Intended for
!Informal use
!us alternative
|-
|rowspan="3"|[[.la|la]]
|rowspan="3"|{{Flag|Laos}}
|{{Flag|Louisiana}}
|la.us
|-
|rowspan="2"|{{Flag|Los Angeles}}<ref name="investvine">{{cite web |url=http://investvine.com/laos-sells-la-domain-to-los-angeles-businesses/ |title=Laos rents '.la' Internet domain to Los Angeles businesses |first=Arno |last=Maierbrugger |work=Inside Investor |date=10 July 2013 |access-date=11 July 2013 |archive-url=https://web.archive.org/web/20130914043412/http://investvine.com/laos-sells-la-domain-to-los-angeles-businesses/ |archive-date=2013-09-14 |url-status=live }}</ref>
|la.ca.us
|-
|los-angeles.ca.us
|-
|[[.mn|mn]]
|{{Flag|Mongolia}}
|{{Flag|Minnesota}}<ref>{{Cite web |last=DomainNRG |title=StateFair.MN and DomainNRG Launch the “Most Minnesotan” Domain Name Competition |url=https://www.prweb.com/releases/statefair_mn_and_domainnrg_launch_the_most_minnesotan_domain_name_competition/prweb11051568.htm |access-date=2025-03-20 |website=www.prweb.com |language=en}}</ref>
|mn.us
|-
|[[.ms|ms]]
|{{Flag|Montserrat}}
|{{Flag|Mississippi}}<ref>{{Cite web |url=http://www.dixie-net.com/msdomains.shtml |title=Mississippi Company Has Unique Product To Personalize Email Addresses |access-date=26 November 2018 |archive-url=https://web.archive.org/web/20100503100700/http://www.dixie-net.com/msdomains.shtml |archive-date=3 May 2010 |url-status=dead |df=dmy-all }}</ref>
|ms.us
|}

== See also ==
*[[Internet in the United States]]
*{{section link|List of Internet top-level domains|North America}}

== References ==
{{Reflist|2}}

== Further reading ==
* {{cite book|title=Addressing the World: National Identity and Internet Country Code Domains|first=Erica Schlesinger|last=Wass|location=Lanham, Maryland|publisher=[[Rowman & Littlefield]]|date=2003|isbn=9780742528109|url=https://books.google.com/books?id=PbOYUSwNxaYC&pg=PA127|via=Google Books}}

== External links ==
* [https://www.about.us/ ''us'' Domain Registry]
* [http://telecafe.org/smw/.US_Locality_Domains .US Locality Domains] {{Webarchive|url=https://web.archive.org/web/20170218194305/http://telecafe.org/smw/.US_Locality_Domains |date=February 18, 2017 }} - A wiki page showing instructions for registering a fourth-level ''us'' locality domain name.
* [https://www.iana.org/domains/root/db/us.html IANA ''us'' whois information]
* [http://www.ntia.doc.gov/legacy/ntiahome/domainname/usca/index.html Domain Names: ''Management of Internet Names and Addresses'' ''us'' Domain Space] {{Webarchive|url=https://web.archive.org/web/20141003081705/http://www.ntia.doc.gov/legacy/ntiahome/domainname/usca/index.html |date=October 3, 2014 }}
* [http://www.neustar.us/the-ustld-nexus-requirements/ usTLD Nexus Requirements] {{Webarchive|url=https://web.archive.org/web/20121031085221/http://www.neustar.us/the-ustld-nexus-requirements/ |date=October 31, 2012 }} - Requirements for registrants of ''us'' domains
* {{IETF RFC|1480}}: The US Domain (June 1993)
* {{webarchive |url=https://web.archive.org/web/20000302160122/http://www.nic.us/usdom-overview.html#Delegation |date=March 2, 2000 }}

{{United States top-level domains}}
{{ccTLD|state=collapsed}}
{{United States topics}}
{{Americas topic|Internet in }}

{{DEFAULTSORT:Us}}
[[Category:Country code top-level domains]]
[[Category:Domain names in the United States]]
[[Category:Council of European National Top Level Domain Registries members]]
[[Category:Internet properties established in 1985]]
[[Category:Acts of the 107th United States Congress]]

[[sv:Toppdomän#U]]