Hornbrook is a census-designated place (CDP) in Siskiyou County, California, United States.

It was named by the Southern Pacific Railroad in 1886, derived from the brook that ran through David Horn's property.

[3] According to the United States Census Bureau, the CDP has a total area of 1.2 square miles (3.1 km2), 99.04% of it land and 0.96% of it water.

This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F (22.0 °C).

There were 156 housing units at an average density of 132.6 per square mile (51.2/km2), of which 72 (66.7%) were owner-occupied, and 36 (33.3%) were occupied by renters.

About 19.8% of families and 21.3% of the population were below the poverty line, including 30.3% of those under the age of eighteen and 13.0% of those 65 or over.

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

Fighter Pilot Ace - WWII - Distinguished Flying Cross - Missing in Action 1944 - Born in Hornbrook, CA 1922