|Original Idaho Territory with general county boundaries.|
Adapted from J. H. Hawley with future borders tinted in color.
Created in 1863 [blog, Mar 4], the initial Territory included all of future Montana and Wyoming. The first Idaho Territorial legislature adjusted many of the county definitions “inherited” within the former boundaries of Washington Territory. They reduced or redefined the four counties west of the Continental and Bitteroot divides – Boise, Idaho, Nez Perces, and Shoshone – to include three new entities: Alturas, Oneida, and Owyhee counties.
That first legislature also defined ten counties to the east. However, in May 1864, most of those counties became part of the new Montana Territory, or were returned to Dakota. With all those areas removed, Idaho had to define new legislative districts, and decided to also modify the Territory’s county structure.
On December 22nd, the legislature created three more counties. By then, prospectors had discovered immensely valuable gold fields in the Boise Basin. Idaho City, the county seat of Boise County, was by far the most populous town in the Territory. However, the city’s population was in a constant state of flux as prospectors and businessmen chased the latest gold rushes around the Boise Basin.
Boise City, tiny by comparison, had a solid core of businesses that served the rapidly growing farm and ranch population of the Boise Valley. It was also the transportation and freight hub of southwest Idaho. Those economic realities promised a bright future of stability and steady growth. Thus, the legislature partitioned western sections of Boise and Idaho county to create Ada County. They made Boise City the county seat. (Just a couple days later they made it the Territorial capital.)
|Idaho Territory, 1865.|
Adapted from J. H. Hawley.
Kootenai County finally received a boost when Northern Pacific Railroad tracks entered the area in 1880, followed by much new settlement. The county formally organized in 1881 and selected Rathdrum as the county seat. The seat moved to Coeur d’Alene after Bonner County was split off in 1908.
Latah County followed a much different – and rather bizarre – route. That area grew much more rapidly, and the inhabitants soon began to press for their own county offices. However, officials in Nez Perce County opposed such a move since they handled those functions (and the attendant budget). Locals finally executed a desperate ploy: Latah County has the distinction of being the only county organized by an act of the U. S. Congress (in May 1888).
|“Ada County,” Reference Series No. 300, Idaho State Historical Society (July 1967).|
|“The Creation of the Territory of Idaho,” Reference Series No. 264, Idaho State Historical Society (March 1969)|