The nation's most urban counties continue to grow faster than any other county type, according to the Census Bureau's 2016 county population estimates. A “Demo Memo” analysis of 2010 to 2016 county population trends along the Rural-Urban Continuum documents ongoing metro growth (the bigger, the better) and continuing rural decline.

The Rural-Urban Continuum (RUC) is the federal government's way of classifying counties by their degree of urbanity. The continuum is a scale ranging from 1 (the most urban counties, in metropolitan areas of 1 million or more) to 9 (the most rural counties, lacking any settlements of 2,500 or more people and not adjacent to a metropolitan area).

If you sort the nation's 3,000-plus counties by their rank on the continuum, then measure population change between 2010 and 2016 for each rank, this is the result...

County Population Change 2010-2016 by RUC Rank

1. 6.0% for rank 1 counties, in metros with 1 million+
2. 4.6% for rank 2 counties, in metros of 250,000 to 1 million
3. 3.0% for rank 3 counties, in metros with less than 250,000
4. 0.2% for rank 4 counties, non-metro adjacent to metro with urban population of 20,000+
5. 1.7% for rank 5 counties, non-metro not adjacent to metro with urban population of 20,000+
6. -1.0% for rank 6 counties, non-metro adjacent to metro with urban population of 2,500-19,999
7. -1.1% for rank 7 counties, non-metro not adjacent to metro with urban population of 2,500-19,999
8. -1.3% for rank 8 counties, non-metro adjacent to metro with urban population less than 2,500
9. -1.6% for rank 9 counties, non-metro not adjacent to metro, urban population less than 2,500

An examination of annual rates of population change by RUC shows population declines in every year between 2010 and 2016 for counties ranking 6, 7, 8, and 9 on the continuum. Counties with a rank of 1 on the continuum (the most urban) grew faster than any other county type in every year.