Foresthill is a census-designated place (CDP) in Placer County, California, United States. It is part of the Sacramento–Arden-Arcade–Roseville Metropolitan Statistical Area. The population was 1,483 at the 2010 census, down from 1,791 at the 2000 census.
Foresthill is located on a broad ridge between the North and Middle Forks of the American River on the gold-bearing gravel bed of an ancient river. In the spring of 1850, miners came to the Forest Hill Divide in large numbers. There was one route from Auburn through Yankee Jim's and one from Coloma. At the junction of these trails, the Forest House hotel and trading post was built. The height of mining activity in Forest Hill began in 1853 after a winter landslide at the head of Jenny Lind Canyon exposed numerous nuggets of gold. The Jenny Lind mine produced about $2,500 of gold a day for a while, up to a total output over $1 million by 1880. The combined production of all the mines in the Forest Hill area was estimated at $10 million by 1868 with gold selling for $16 an ounce. In the 1860s, there were about 125,000 feet (38,000 m) of hard-rock tunnels dug into the hillsides in, around and under Forest Hill. By 1857, this area had become an important center for trade among the many gold camps on the divide. In 1862, the Hardy-Kennedy building was erected - the first fireproof store in Forest Hill. This building, now known as the Langstaff building, is still being used by the merchants of Foresthill. By 1880, Forest Hill was one of the largest towns in Placer County. The town had an 80-foot (24 m) wide main street befitting such an important place.
Today the town has a marker identifying it as a California Historical Landmark.