The population count of Maricopa County, AZ was 4,253,913 in 2018. The population count of San Bernardino County, CA was 2,135,413 in 2018. The population count of Clark County, NV was 2,141,574 in 2018.
Population
Population Change
Above charts are based on data from the U.S. Census American Community Survey | ODN Dataset | API -