Of Idaho’s 44 counties, Jerome waltzed in at No. 43 less than a century ago, just a week behind Clark County and three days ahead of Caribou County.
The Idaho Legislature carved Jerome County out of Lincoln County in 1919, nearly 30 years after Idaho became a state.
But the history of what would become Jerome County is not nearly that simple.
As part of Washington Territory, Idaho had been divided into four counties: Nez Perce, Shoshone, Idaho and Boise, with Boise County covering the southern half the territory. When Idaho became a territory in 1863, the four original counties stayed intact but were unrecognized by the territorial legislature.
On Dec. 31, 1863, the legislature designated all land south of the Snake River as Owyhee County; a month later, Oneida County was created from the east end of Owyhee.
After another month, the now-defunct Alturas County was created in the center of what had been Boise County in Washington Territory. Alturas, from a Spanish word meaning “mountain summits,” then included parts of modern-day Custer, Lemhi, Clark, Jefferson, Fremont, Bonneville, Bingham, Power, Elmore and Boise counties, and all of Camas, Blaine, Butte, Minidoka, Lincoln, Gooding and Jerome counties.
Rocky Bar, a mining camp in the center of the the county, became the seat. In 1882, the county seat moved to Hailey.
In 1889, just a year before Idaho gained statehood, the legislature carved Elmore County and the now-defunct Logan County from Alturas County. Logan County extended from just north of Bellevue to the Snake River. Later, the legislature abolished both counties and formed Lincoln and Alta counties. The Idaho Supreme Court quickly declared the move unconstitutional and returned Alturas and Logan counties to existence.
Five years into statehood, Alturas and Logan again disappeared as the two counties merged to create Blaine County. A month later, Lincoln County — which included today’s Gooding, Jerome and Minidoka counties — split from Blaine. In 1913, Gooding and Minidoka counties were carved from Lincoln.
Finally, Jerome County — one of the smallest in the state — was carved from Lincoln County in February 1919.