Thunder Valley Motocross Park was founded in June of 1999, promoter David Clabaugh couldn’t have known how appropriate his track’s name would become. He knew that nearby was an NHRA drag-racing track with the same name (Thunder Valley), but within a few short years of the founding of the motocross track, four-strokes took over motocross completely, leaving a sound of thunder every time the gate drops at the facility.
Thunder Valley, just a few miles below downtown Denver, hosted its first AMA Pro Motocross National in July of 2005. In the first few years of racing at the facility, riders and mechanics were met with a combination of altitude and summertime heat that not only made it physically difficult on them but caused the fuel in the motorcycles to literally boil.
Thunder Valley hosted the first AMA Pro Motocross National ever held at night, under a battery of lights that illuminated the valley. With a live internet and TV audience watching, the race was a smash hit.