Callahan is an unincorporated community in Siskiyou County, California, United States.

Callahan is located on California State Route 3 11.5 miles (18.5 km) south-southeast of Etna.

Callahan, who opened a travelers' stop[clarification needed] in the community in 1851.

[3] During the Civil War the local butcher shop raised a Palmetto flag to show support for the rebels but it was soon hauled down with 2 townspeople heckling the owner about it.

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