List of All Counties in Idaho

There are a total of 44 counties in the state of Idaho. Among them, Owyhee County is the oldest one (established in 1863) while Caribou County is the youngest (established in 1919).  With population of 392,365, Ada County is the most populated. The biggest county by land area is Idaho County (21,976 km²) and the smallest is Payette County (1,057 km²). Below please see all Idaho counties which are listed in alphabetical order.

Map of Idaho Counties

Map of Idaho Counties