Ranking of Idaho Counties By Total Voting-age Population (18yrs and over) from Census 2020

According to the data from the US 2020 Census, as at April 2020, among all the counties in Idaho, Ada County had the highest voting-age population (18 years and over) (378.48K), followed by Canyon County (166.44K), and Kootenai County (132.21K).

The chart below shows the top 10 counties with high voting-age population, and the table below shows the ranking of all Idaho counties based on voting-age population.

You can also see the ranking of counties by population for other states as well as for the whole United States.