On February 11 Idaho will pass another anniversary, six years away from the centennial mark since it last created a new county. Caribou County, hacked away from Bannock County in 1919, is the youngest, though by only three days: Jerome County was formed the previous Saturday, its territory taken from Gooding and Lincoln counties (Jerome being situated in the middle).
These were not rare instances. Twenty counties, almost half of Idaho's current 44, were formed in the decade of the 1910s, all carved out of pieces of other counties. Most have in common relatively small geographical areas and small to midsized populations. Idaho's smallest county, Payette, was formed in 1917 from Canyon County. There was Adams in 1911 (from Washington), Benewah in 1915 (from Kootenai), Boundary in 1915 (from Bonner), Camas in 1917 (from Blaine), Lewis in 1911 (from Nez Perce), and so on. Many more Idaho counties were formed in the 1910s than in any other decade.
One reason may have been a population boom. Idaho's head count doubled from 1900 to 1910, and by about half again during the 1910s. Many of the counties that split up in the 1910s had experienced huge growth; Lincoln County, which was split three times, went from 1,784 people in 1900 to 12,676 in 1910. In 1920, after the cut-ups, Lincoln was back down to 3,446, territory where it has remained since.
Another reason probably was transportation, and transportation expectations. The first two decades of the twentieth was transitional, between an established but lightly-populated state, and a state with significant population. In 1900 Idaho's population was about 162,000, fairly close to Nampa plus Meridian today. In 1920 it reached 432,000, making Idaho a whole different kind of place. Commerce and other reasons for travel were booming. (more…)