In 1864, Idaho Territorial Legislator H.C. Riggs introduced a bill to create a new county. As a result, Ada County was established on December 22, 1864. For his efforts, the county was named after Riggs’ eight-year-old daughter Ada Hobbs Riggs. Ada County celebrated its Sesquicentennial (150th) Anniversary on December 22, 2014.
Board of Ada County Commissioners Proclamation
Including a brief history of Ada County