The nation's most urban counties grew by a substantial 6.0 percent between 2010 and 2016, faster than any other type, according to a Demo Memo analysis of the Census Bureau's 2016 county population estimates by Rural-Urban Continuum (RUC). Counties in smaller metros grew at a slower rate, and those in rural areas lost population. Both international and domestic migration contributed to the faster growth of big-city counties...
International migration is greater in big-city counties. Between 2010 and 2016, the rate of net international migration was 2.6 percent in counties ranking 1 on the Rural-Urban Continuum. Although international migration was positive in every type of county, the rate was lower in less urban counties and lowest (only 0.3 percent) in the most rural counties—those ranking 8 or 9 on the RUC.
Domestic migration is positive only in big-city counties. Between 2010 and 2016, the rate of net domestic migration was positive only for counties ranking 1 or 2 on the Rural-Urban Continuum. Nonmetropolitan counties (those ranking 4 or higher on the RUC) had a negative rate of net domestic migration, meaning they lost more people than they gained.
Source: USDA, Economic Research Service, Rural-Urban Continuum Codes and Census Bureau, County Population Totals Datasets: 2010–2016