Comparing population growth over five-year periods helps identity areas in the U.S. with recent and significant downturns in population.
Commercial real estate firm CBRE analyzed the population growth in U.S. counties from 2010 to 2015 and then from 2016 to 2021 to arrive at a percentage point difference it sees as a momentum shift — the greatest deceleration of population growth, not simply growth overall.
"Understanding the shifting momentum of population growth over an entire decade can help put the recent trends into a broader context and identify markets that are gaining momentum, even if their overall growth remains modest," the firm's Oct. 2022 analysis states. "Should such momentum continue, some of these markets could provide emerging investment opportunities."
What's the difference between momentum shift and overall growth? The counties containing Detroit and Austin, Texas, make for prime examples of two different ways of measuring population trends. Detroit's county saw -3.2 percent population loss from 2010 to 2015, and 1.5 percent growth from 2016 to 2021 — a percentage point difference of 4.7. Austin's county saw 14 percent population growth from 2010 to 2015 and 8.8 percent growth from 2016 to 2021 — a percentage point difference of -5.2. While Austin may have recorded more growth overall, Detroit has experienced more positive momentum.
Below are the top 18 counties with population exceeding 500,000 in 2021 for negative momentum growth, ranked by their percentage-point shift between time periods.
1. San Francisco County (California): -13.4 percentage point shift
2010-2015: 7 percent
2016-2021: -6.4 percent
2. Washington, D.C.: -12.4 percentage point shift
2010-2015: 10.8 percent
2016-2021: -1.6 percent
3. Denver County (Colorado): -10 percentage point shift
2010-2015: 12.7 percent
2016-2021: 2.7 percent
4. San Mateo County (California): -9.5 percentage point shift
2010-2015: 6 percent
2016-2021: -3.5 percent
5. Miami-Dade County (Florida): -9.2 percentage point shift
2010-2015: 7.4 percent
2016-2021: -1.8 percent
6. Suffolk County (Massachusetts): -8.8 percentage point shift
2010-2015: 7.1 percent
2016-2021: -1.7 percent
7. Santa Clara County (California): -8.7 percentage point shift
2010-2015: 6.9 percent
2016-2021: -1.8 percent
8. Alameda County (California): -7.8 percentage point shift
2010-2015: 7.9 percent
2016-2021: 0.1 percent
9. New York County / Manhattan: -7.4 percentage point shift
2010-2015: 3.3 percent
2016-2021: -4.1 percent
10. Harris County (Texas): -7.3 percentage point shift
2010-2015: 10.3 percent
2016-2021: 3 percent
11. San Diego County (California): -7 percentage point shift
2010-2015: 6 percent
2016-2021: -1 percent
12. Dallas County (Texas): -6.9 percentage point shift
2010-2015: 7.3 percent
2016-2021: 0.4 percent
13. Arapahoe County (Colorado): -6.7 percentage point shift
2010-2015: 9.5 percent
2016-2021: 2.8 percent
14. Broward County (Florida): -6.6 percentage point shift
2010-2015: 7.7 percent
2016-2021: 1.1 percent
15. Multnomah County (Oregon): -6.5 percentage point shift
2010-2015: 7 percent
2016-2021: 0.5 percent
- Bronx County (New York): -6.5 percentage point shift
2010-2015: 4.4 percent
2016-2021: -2.1 percent
16. Baltimore (Maryland): -6.2 percentage point shift
2010-2015: 0 percent
2016-2021: -6.2 percent
17. Los Angeles County (California): -5.9 percentage point shift
2010-2015: 2.9 percent
2016-2021: -3 percent