The city of Grass Valley is the largest city in the western region of Nevada County, California, United States. Situated at roughly 2,500 feet elevation in the western foothills of the

Sierra Nevada mountain range, this historic northern Gold Country city is located 75 miles  by car from the state capitol in Sacramento, 64 miles from Sacramento International Airport, 90 miles west of Reno, Nevada, and 175 miles northeast of San Jose, California. As of the 2010 United States Census, the population is stated as 12,860.

Grass Valley, which was originally known as Boston Ravine and later officially named Centerville, dates from the California Gold Rush, as does nearby Nevada City. When a post office was established in 1851 it was renamed Grass Valley  the following year for unknown reasons. The town incorporated in 1860.

Grass Valley is the location of the Empire Mine and North Star Mine, two of the richest mines in California. Many of those who came to settle in Grass Valley were tin miners from Cornwall, England. They were attracted to the California gold fields because the  same skills needed for deep tin mining were needed for hardrock (deep)  gold mining. Many of them specialized in pumping the water out of very  deep mining shafts. This followed the disastrous fall in tin prices as  large alluvial deposits began to be exploited elsewhere.

Grass Valley still holds on to its Cornish heritage, with events such as its annual Cornish Christmas and St Piran’s Day celebrations.Pasties are a local favorite dish with a few restaurants in town specializing  in recipes handed down from the original immigrant generation. Grass  Valley is also twinned with the Cornish town of Bodmin, UK.

There was formerly a Roman Catholic diocese of Grass Valley.