Union Hill is a former settlement in Nevada County, California, 1.5 mi (2.4 km) from Grass Valley.

[3] The Union Hill School District, established in 1868, continues to operate in Grass Valley, though at a different location.

Beginning in 1876, travelers could reach Union Hill via the Nevada County Narrow Gauge Railroad.

[4] Its station was located on the Union Hill road, southeast of Grass Valley and northwest of Colfax.

[5] The Union Hill mine was a good producer of gold for many years.