The U.S. Census Bureau estimates that the nation’s population increased from 328.3 million (July 2019) to 329.4 million (July 2020) — adding 1.5 million new residents. On average, the U.S. population has increased 2.0 percent over the past five years.
Idaho had the fastest growth rate with a 2.1 percent growth rate over the past year followed by Arizona (1.8 percent). Rounding out the list of most rapidly growing states are Nevada (1.5 percent), Utah (1.5), Texas (1.3 percent) and South Carolina (1.2 percent). Population totals decreased in eight states: New York (-0.6), Illinois (-0.6), Hawaii (-0.6), West Virginia (-0.6), Mississippi (-0.3 percent), Alaska (-0.4 percent), Alaska (-0.3 percent), and Louisiana (-0.3 percent).
The most populous states in the US are California (39.4 million), Texas (29.3), Florida (21.7), New York (19.3), Pennsylvania (12.8) and Illinois (12.6). States with the largest one-year, July-to-July, population gains were Texas (+374,000), Florida (+241,300), Arizona (+129,600), and North Carolina (+99,400).
Missouri ranked 18th by population size with 6,151,548 residents. The state gained 11,073 new residents between July 2019 and July 2020. Neighboring Tennessee added 56,500 residents; neighboring Illinois lost 79,500 residents. Tennessee and Oklahoma had the largest one-year percentage increases among states that surround Missouri: 0.8 and 0.5 percent, respectively. Arkansas and Nebraska grew by 0.3 percent while Missouri and Kentucky each grew by 0.2 percent and 0.1 percent respectively. Kansas maintained it population from the previous year.
For 2020 Missouri counties population St. Louis County had the largest Missouri population with 994,020 residents followed by Jackson County with 705,925 residents, St. Charles County with 406,204 residents, St. Louis City with 297,645 residents, and Greene County with 294,997 residents. The county with the smallest population in Missouri is Worth County with 1,953 residents.
Missouri Counties with the largest one year (2019 to 2020) increase in population include St. Charles County with 4,579 population growth, Clay County with 2,941 population growth, Boone County with 1,907 population growth, and Platte County with 1,806 population growth. Greatest loss of population between 2018 and 2019 was found in St. Louis City with 3,242 population decline and St. Louis County with 1,447 population decline.