[8] Quincy started as a Gold Rush town, associated with the former Elizabethtown, California.

Development moved a mile away into the American Valley after settler James H. Bradley, who helped organize Plumas County, donated land there for the county seat.

[9] The Quincy post office opened in 1855,[5] and the town was formally recognized in 1858.

[10] According to the United States Census Bureau, the CDP has a total area of 4.2 square miles (11 km2), all of it is land.

Quincy is underlain by metasedimentary rock of the Shoo Fly Complex.

[11] Its dominant silica-rich clastic material weathers to a stony coarse soil which includes the well or somewhat excessively drained alluvial fan material (mainly Forgay very gravelly sandy loam) on which most of Quincy's businesses and homes have been built.

[12] Quincy has a Mediterranean climate (Köppen Csb) though its inland location and altitude makes it more continental and wetter than usual for this type, with very heavy snowfalls sometimes occurring in winter – the record being 133 inches (337.8 cm) in the very wet January 1916.

There were 899 housing units at an average density of 212.2 per square mile (81.9/km2).

[20] In the California State Legislature, Quincy is in the 1st Senate District, represented by Republican Megan Dahle, and in the 1st Assembly District, represented by Republican Heather Hadwick.

[21] Federally, Quincy is in California's 1st congressional district, represented by Republican Doug LaMalfa.