Gem County, Idaho County, Idaho were: Gem County, Idaho Gem County is a county in the U.S. state of Idaho. As of the 2010 census, the population was 16,719. The county seat and largest city is Emmett. Gem County is part of the Boise, ID Metropolitan Statistical Area. Gem County is home to the Idaho ground squirrel. Named for the state nickname, "Gem State," the county was established on March 15, 1915, partitioned from Canyon County and Boise County. Fur trappers were in the area as early as 1818, and Alexander Ross explored Squaw Creek in 1824. Prospectors and miners moved through the
Secondary state highways as branches of Primary State Highway 7 (Washington) Route 10 about a mile north of Kittitas. SSH 7B was removed from the state highway system in 1953. The route is not part of the modern Washington state route system. When it was added to the state highway system in 1951, Secondary State Highway 7C originated at US 10/PSH-7 at the east end of the Vantage Bridge, at a point where the main highway turned north to climb out of the Columbia River Valley. From the banks of the Columbia, SSH 7C headed east to a junction with US 395/PSH 11 west of Othello, remaining roughly parallel to US