The 2021 NAPA Auto Parts Colorado 150 was a ARCA Menards Series West race held on July 31, 2021. It was contested over 150 laps on the .375-mile (0.604 km) short track oval. It was the fourth race of the 2021 ARCA Menards Series West season. David Gilliland Racing driver Joey Iest, collected his first career ARCA Menards Series West win.