Grass Valley is a city in Nevada County, California, United States. Situated at roughly 2,500 feet elevation in the western foothills of the Sierra Nevada mountain range, this northern Gold Country city is 57 miles by car from Sacramento, 64 miles from Sacramento International Airport, 88 miles west of Reno, and 143 miles northeast of San Francisco. As of the 2010 United States Census, its population was 12,860.