SAN FRANCISCO (KRON) — New census data reveals some of the United States’ most populous cities experienced some of the largest exoduses of people.

The U.S. Census Bureau’s first release of population estimates for cities and towns this decade shows some of the fastest-growing cities before the pandemic grew at a much slower rate after it started.

Cities experiencing population decline

San Francisco was not among the 15 fastest-declining cities in 2019 but topped the list of cities experiencing the fastest decline in population in 2021 with a 6.3% drop from the previous year. According to census data, six of the cities on the list of cities with a population decline in 2021 were in California.

Only one city was among the 15 fastest-declining in both 2019 and 2021 — Cupertino — the magnitude of the drop (in its population growth rate) nearly tripled.

Overall, pre-pandemic population losses between 2018 and 2019 were much lower than after the pandemic hit. In Petaluma, the city recorded the largest population decline from July 1, 2018, to July 1, 2019, a drop of 2.1%. According to the data, Petaluma’s drop in population would not even have ranked among the top 15 in 2020-2021, after the start of the pandemic.

Officials said these rates of population decline of 5% or more in a single year were nearly unprecedented and point to a variety of causes, including natural disasters such as hurricanes and wildfires for people to pick up and leave town.

Small town population trends

The 2021 population estimates released Thursday also provide a regional perspective on growth in cities and towns of all sizes.

On average, small towns with populations of less than 5,000 experienced uneven growth across U.S. regions:

  • In the Northeast, the populations of small towns decreased on average by 0.2%.
  • In the Midwest, small towns experienced no change on average.
  • In the South, small towns grew on average by 0.4%.
  • In the West, small towns saw the largest growth, with an average increase of 1.1%.