Thunderhill Raceway Park

Thunderhill Raceway Park is a road-racing complex set in the Sacramento Valley about 7 miles west of Willows, California. Owned and operated by the San Francisco Region of the Sports Car Club of America, it is best known as the home of the 25 Hours of Thunderhill, the longest automobile endurance race in the United States, run every December.

The facility actually offers more than one course. The original layout, known as Thunderhill East, is a 2.866-mile, 15-turn circuit with rolling elevation changes that flow with the natural terrain. A separate 2.0-mile Thunderhill West track opened in 2014, and the two can be linked into a roughly 5-mile configuration that briefly ranked as the longest racetrack in California and earned the nickname "Thunderschleife" in honor of the Nurburgring Nordschleife. Large skid pads round out the site for drifting and car-control work.

Built in 1993 as a shorter 9-turn course and expanded to its current form in 1997, Thunderhill matters to drivers because its blend of fast sweepers, blind crests, and technical complexes rewards precise car placement and commitment. That variety makes it an ideal proving ground for driver development, from first track days through wheel-to-wheel competition.