Interstate 129

2025-08-06T21:39:01Z

2601:98B:8001:5920:8975:E0F2:709C:9FBF:

{{Short description|Highway in Iowa and Nebraska}}
{{Use American English|date=April 2025}}
{{Use mdy dates|date=March 2015}}
{{Infobox road
|country=USA
|type=I
|route=129
|map={{maplink-road|from=Interstate 129.map}}
|map_custom=yes
|map_notes=I-129 highlighted in red
|length_mi=3.50
|length_ref=<ref name=NDOR>{{cite web|title=Nebraska Highway Reference Log Book|url=http://www.roads.nebraska.gov/media/6920/logbook.pdf|publisher=Nebraska Department of Roads|access-date=January 8, 2017|page=270|date=2015|archive-date=January 2, 2017|archive-url=https://web.archive.org/web/20170102171736/http://www.roads.nebraska.gov/media/6920/logbook.pdf|url-status=dead}}</ref><ref name=DOTGIS>{{cite web |title=Road Network (Portal) |url=https://gis.iowadot.gov/agshost/rest/services/RAMS/Road_Network/FeatureServer/0 |publisher=Iowa Department of Transportation |access-date=April 18, 2021 |location=Ames |format=[[ESRI shapefile]] |date=April 9, 2021}}</ref>
|length_notes=Nebraska: {{convert|3.21|mi|abbr=on}}<br>Iowa: {{convert|0.286|mi|m|abbr=on}}
|established=November 22, 1976<ref name="DOT Interstates">{{cite book|last=Iowa Department of Transportation|author-link=Iowa Department of Transportation|title=The National System of Interstate Defense Highways: 1956–1996}}</ref>
|direction_a=West
|terminus_a={{Jct|state=NE|US|20}} in [[South Sioux City, Nebraska|South Sioux City, NE]]
|junction={{Jct|state=NE|US|75|US|77}} in South Sioux City, NE
|direction_b=East
|terminus_b={{Jct|state=IA|I|29|US|20|US|75}} in [[Sioux City, Iowa|Sioux City, IA]]
|states={{flatlist|
*[[Nebraska]]
*[[Iowa]]
}}
|counties={{flatlist|
*'''NE'''
**[[Dakota County, Nebraska|Dakota]]
*'''IA'''
**[[Woodbury County, Iowa|Woodbury]]
}}
|browse={{ne browse|previous_type=NE|previous_route=128|route=[[List of Nebraska numbered highways|NE]]|next_type=NE|next_route=133}}{{ia browse|previous_type=IA|previous_route=128|route=[[List of state highways in Iowa|IA]]|next_type=IA|next_route=130}}
|spur_type=I
|spur_of=29
}}

'''Interstate 129''' ('''I-129''') is an auxiliary Interstate Highway which connects [[South Sioux City, Nebraska]], to [[Interstate 29 in Iowa|I-29]] in [[Sioux City, Iowa]]. Opened in 1976, I-129 is a {{convert|3.5|mi|km|adj=mid|-long}} route, running {{convert|3.21|mi|km}} in [[Nebraska]]. At {{convert|0.286|mi|km}}, I-129 is the shortest highway in the state of Iowa. All of the route's length is concurrent with [[U.S. Route 20]] (US 20) and most of its length is concurrent with [[U.S. Route 75|US 75]].

==Route description==
I-129 begins along [[U.S. Route 20 in Nebraska|US 20]] on the western edge of [[South Sioux City, Nebraska]], just west of exit 1, a [[cloverleaf interchange]] with [[U.S. Route 75 in Nebraska|US 75]] and [[U.S. Route 77 in Nebraska|US 77]]. US 77 travels north through South Sioux City before ending at [[Interstate 29 in Iowa|I-29]] in [[Sioux City, Iowa|Sioux City]] while US 75 joins I-129 and US 20. {{convert|1|mi|km|spell=In}} later, I-129/US 20/US 75 intersect Dakota Avenue at a [[partial cloverleaf interchange]]. [[U.S. Route 20 Business (South Sioux City, Nebraska)|U.S. Highway 20 Business]] (US 20 Bus.) is designated along Dakota Avenue.<ref name=NDOR/>

East of Dakota Avenue, I-129/US 20/US 75 travels south of South Sioux City and passes through rolling farmland. For the rest of I-129's length, the two directions of I-129/US 20/US 75 traffic are separated by a [[Jersey barrier]] instead of a grassy median. The three routes cross the [[Missouri River]] and immediately intersect [[Interstate 29 in Iowa|I-29]] at an interchange. Due to the minimum amount of space along the [[Missouri River]] banks, the I-29 interchange is a modified two-level [[Interchange (road)#Combination interchange|cloverstack interchange]]. At I-29, US 20 and US 75 continue east around [[Sioux City, Iowa|Sioux City]] and I-129 ends.<ref>{{Google maps | url = https://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&sll=42.448415,-96.393088&sspn=0.00528,0.009634&g=Sioux+City&ie=UTF8&hq=&hnear=Sioux+City,+Woodbury,+Iowa&t=h&layer=x&ll=42.445834,-96.373959&spn=0.010561,0.019269&z=16 | access-date = February 27, 2010}}</ref>

==History==
After the passage of the [[Federal-Aid Highway Act]] in 1968, the mileage which would eventually be manifested in over {{convert|1400|mi|km}} of Interstate Highway was allocated to the states. Iowa received the smallest allocation, {{convert|0.5|mi|km}}, for the southern bypass of [[Sioux City, Iowa|Sioux City]].<ref name="FHWA Dec 13">{{cite web|url=https://www.fhwa.dot.gov/byday/fhbd1213.htm|title=FHWA By Day - December 13|last=Federal Highway Administration|author-link=Federal Highway Administration|access-date=August 1, 2010}}</ref> The proposed highway was planned to cost $22.5 million (equivalent to ${{inflation|US|22.5|1972|r=2}} million in {{inflation/year|US}}), which included $15 million (equivalent to ${{inflation|US|15|1972|r=2}} million in {{inflation/year|US}}) for the Missouri River bridge.<ref>{{cite news|title=Hot off the Wire|url=https://www.newspapers.com/clip/838464/hot_off_the_wire/|access-date=August 9, 2014|work=[[Carroll Daily Times Herald]]|location=Carroll, Iowa|date=June 2, 1972|pages=2|via=[[Newspapers.com]]}}{{open access}}</ref> On the 1973 state highway map, the [[Iowa State Highway Commission]] showed the planned route on the state map for the first time.<ref name=DOT1973>{{Cite IowaDOT map|access-date=August 1, 2010|year=1973|inset=Sioux City}}</ref> I-129 was opened on November 22, 1976.<ref name="DOT Interstates"/>

{{clear}}

==Exit list==
{{jcttop|exit|state_col=State|length_ref=<ref name="NDOR"/><ref name=DOTGIS/>}}
{{NEint|exit
|sspan=3
|county=Dakota
|cspan=3
|location=Covington Precinct
|ctdab=Dakota
|lspan=2
|type=concur
|mile=0.00
|road={{Jct|state=NE|US|20|dir1=west}}
|notes=Western end of US 20 concurrency; continuation beyond western terminus
}}
{{NEint|exit
|type=concur
|mile=0.38
|mile2=0.40
|exit=1
|road={{Jct|state=NE|US|75|dir1=south|US|77|location1=Fair Grounds|location2=[[Sioux City, Iowa|Sioux City]]}}
|notes=Western end of US 75 concurrency; signed as exits 1A (south) & 1B (north)
}}
{{NEint|exit
|location=South Sioux City
|mile=1.50
|exit=2
|road={{jct|state=NE|road|Dakota Avenue|name1=[[U.S. Route 20 Business (South Sioux City, Nebraska)|US 20 Bus.]] east|city1=South Sioux City|city2=Dakota City}}
|notes=Western terminus of US 20 Bus.
}}
{{Jctbridge|exit
|mile=3.21
|mile2=0.000
|line=yes
|river=[[Missouri River]]
|river_wide=yes
|bridge=Sergeant Floyd Memorial Bridge; [[Nebraska]]–[[Iowa]] line
}}
{{IAint|exit
|sspan=2
|county=Woodbury
|cspan=2
|location=Sioux City
|lspan=2
|type=concur
|mile=0.286
|mspan=2
|exit=1
|road={{Jct|state=IA|I|29|US-Bus|75|dab2=Sioux City|dir2=north|city1=Council Bluffs|location2=[[Sioux Gateway Airport]]|location3=Downtown Sioux City}}
|notes=Eastern end of US 20 and US 75 concurrencies; eastern terminus of I-129; southern terminus of US 75 Bus.; signed as exits 1A (south) and 1B (north); I-29 exits 144A-B
}}
{{IAint|exit
|mile=none
|road={{Jct|state=IA|US|20|dir1=east|US|75|dir2=north|city1=Fort Dodge|city2=Le Mars}}
|notes=Continuation beyond I-29
}}
{{Jctbtm|col=8|keys=concur}}

==References==
{{Reflist}}

{{Attached KML}}
{{3di|29}}

{{start srbox}}
{{ia browse|previous_type=IA|previous_route=128|route=[[List of Iowa state highways|IA]]|next_type=IA|next_route=130}}
{{ne browse|previous_type=NE|previous_route=128|route=[[List of Nebraska numbered highways|NE]]|next_type=NE|next_route=133}}
{{s-end}}

[[Category:Auxiliary Interstate Highways|29-1]]
[[Category:Interstate Highways in Nebraska|29-1]]
[[Category:Interstate Highways in Iowa|29-1]]
[[Category:U.S. Route 20]]
[[Category:U.S. Route 75]]
[[Category:Interstate 29|1]]
[[Category:Transportation in Dakota County, Nebraska]]
[[Category:Transportation in Woodbury County, Iowa]]

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Interstate 129