 Oneida County was officially Idaho Territory's 3rd most populous behind Boise and Ada counties at Idaho Territory's first decennial census in 1870.However, the county's actual population was severely undercounted as a result of its lack of a surveyed southern boundary.The survey of Idaho's southern border by 1872 revealed that the 1870 Census had erroneously assigned eight Idaho settlements in the Bear Lake Valley to Rich County, Utah and five Idaho settlements in the Cache Valley to Cache County, Utah.