View source for Thunderhill Raceway Park

{{Short description|Motorsports complex in Sacramento Valley, California, U.S.}}
{{Use American English|date=July 2025}}
{{Infobox motorsport venue
| name              = Thunderhill Raceway Park
| nicknames         = 
| location          = [[Glenn County, California|Glenn County]], [[Willows, California|Willows]], [[California]]
| coordinates       = {{Coord|39|32|25.2|N|122|19|50.5|W|display=it}}
| logo              =
| image             = [[Image:Thunderhill Raceway Park.svg|class=skin-invert|250px]]
| image_caption     = Thunderhill East Circuit (1997–present)
| track_map         = [[File:Thunderschleife.gif|class=skin-invert|250px]]
| track_map_caption = Thunderschleife Circuit (2014–present)
| capacity          = 
| owner             = 
| operator          = 
| broke_ground      = {{Start date and age|df=yes|1993|01}}
| opened            = 1993
| closed            = 
| construction_cost = 
| architect         = 
| former_names      = 
| events            = '''Current:'''<br />'''[[Trans-Am Series#West coast championship|Trans-Am West Coast Series]]''' (2019–2025)<br />'''Former:'''<br />[[25 Hours of Thunderhill]] (1998–2023)
| miles_first       = True
| layout           = Thunderhill East Circuit (1997–present)
| surface           = Asphalt
| length_km         = 4.612
| length_mi         = 2.866
| turns             = 16
| record_time       =
| record_driver     = 
| record_car        = 
| record_year       = 
| record_class      =
| layout2           = Thunderhill West Circuit (2014–present)
| surface2          = Asphalt
| length2_km        = 3.219
| length2_mi        = 2.000
| turns2            = 20
| record_time2      =
| record_driver2    = 
| record_car2       = 
| record_year2      = 
| record_class2     =
| layout3           = Thunderschleife Circuit (2014–present)
| surface3          = Asphalt
| length3_km        = 7.403
| length3_mi        = 4.600
| turns3            = 42
| record_time3      =
| record_driver3    = 
| record_car3       = 
| record_year3      = 
| record_class3     =
| layout4           = Original East Circuit (1993–present)
| surface4          = Asphalt
| length4_km        = 2.919
| length4_mi        = 1.814
| turns4            = 10
| record_time4      =
| record_driver4    = 
| record_car4       = 
| record_year4      = 
| record_class4     =
}}

'''Thunderhill Raceway Park''' is a [[road racing|motorsports complex]] located {{cvt|7|mi|km|adj=on}} west of [[Willows, California|Willows]], [[California]], [[United States]], in the [[Sacramento Valley]]. It is the venue for the longest automobile race in the United States, the [[25 Hours of Thunderhill]], held annually during the first weekend in December.<ref>{{Cite web |last=Jones |first=Matthew |title=NASA 25 Hours of Thunderhill - Surviving Thunder Hill |url=https://www.motortrend.com/features/1404-nasa-25-hours-of-thunderhill/ |publisher=[[Motor Trend]] |website=motortrend.com |date=9 August 2014 |access-date=13 August 2025}}</ref>

Thunderhill has two tracks: the original {{cvt|2.866|mi|km|abbr=on}} track known as Thunderhill East and a {{cvt|2.000|mi|km|abbr=on}} track known as Thunderhill West. The two tracks can also be combined to offer a {{cvt|4.600|mi|km|abbr=on}} track. Thunderhill also offers two large [[skid pad]] areas as well for [[Drifting (motorsport)|drifting]] and car control events.

The venue is available for a wide variety of events or functions. It can be rented for racing events, lapping day events, drifting events, go kart events, driving schools, ride and drive programs, corporate events, commercials, a movie location, trade shows, weddings, receptions, swap meets etc.

San Francisco Region Properties, Inc., [[Doing business as|dba]] Thunderhill Park is the wholly owned subsidiary of the San Francisco Region Sports Car Club of America. Thunderhill Raceway has its own board of directors and is operated completely independently of the non-profit subsidiary.

==History==

Thunderhill Raceway Park was built in 1993 originally as a {{cvt|1.814|mi|km|abbr=on}}, 9-turn track. Following the closure of the [[Fremont Dragstrip|Baylands Raceway]] in Fremont, CA, the purchase of the land and construction of Thunderhill was funded by the San Francisco Region Sports Car Club of America.

In late 1997, the track was expanded to its present-day {{cvt|2.866|mi|km|abbr=on}} configuration, adding six new turns, a bypass for the "cyclone" corner, and additional paved paddock space.<ref>{{cite web |title=Thunderhill Expansion new release 1997 (Web Archive) |url=http://www.thunderhill.com/News/970626-01.html|archive-url=https://web.archive.org/web/19971015035928/http://www.thunderhill.com/News/970626-01.html |archive-date=1997-10-15 }}</ref>

Thunderhill West was conceptualized in 2013 and built in 2014 as a standalone track. Connectors were made to connect the original track with the new west track to make a five-mile-long track. At the time of construction, this was the longest racetrack in California, and it gained the nickname "Thunderschleife" as a nod to the [[Nürburgring|Nurburgring Nordschleife]].<ref>{{Cite web |last=Lucareli |first=Ben |title=Thunderhill to become one of North America's longest race tracks |url=https://www.roadandtrack.com/motorsports/news/a5332/go-news-racing-thunderhill-raceway-park-longest-road-course-in-america/ |website=roadandtrack.com |date=3 September 2013 |access-date=13 August 2025}}</ref>

==References==
{{Reflist}}

==External links==
{{Commons category}}

*[http://www.thunderhill.com/ Thunderhill Park Official Site]
*[https://www.racingcircuits.info/north-america/usa/thunderhill-raceway-park.html Track information on RacingCircuits.info]
*[http://www.nasa25hour.com/ 25-Hours of Thunderhill Official Site]
*[http://1tail.com/sa/event_organization.htm?g={5C44C492-B225-4763-BB8D-7A5A2EFC0159} 1tail Resource Database - Thunderhill Raceway Park]

{{Trans-Am tracks}}

[[Category:Buildings and structures in Glenn County, California]]
[[Category:Motorsport venues in California]]
[[Category:Willows, California]]
[[Category:Tourist attractions in Glenn County, California]]
[[Category:Road courses in the United States]]