Established March 15, 1915 with its county seat at Emmett. Named for the state nickname, "Gem State." Fur trappers were in the area as early as 1818 and Alexander Ross explored Squaw Creek in 1824. Prospectors and miners moved through the county in 1862 in route to the gold rush in the Boise Basin, and by the next year irrigation began along the Payette River.
County Seat: Emmett
Land Area: 564 square miles