Benewah County Idaho was established in 1915.
Idaho County Idaho was established in 1864.
The total area of Gem County Idaho is, 563 sq mi, (1,459 km sq).
Franklin County Idaho was established in 1913.
Bonneville County Idaho was established in 1911.
Butte County Idaho was established in 1917.
Canyon County Idaho was established in 1892.
Caribou County Idaho was established in 1919.
Cassia County Idaho was established in 1879.
Clark County Idaho was established in 1919.
Clearwater County Idaho was established in 1911.
Custer County Idaho was established in 1881.