Low birth rates, uncertainty over immigration and longterm impacts from COVID-19 will result in a year-over-year population decline in Southern California for the first time ever, researchers said Tuesday in the first of a two-part demographic conference sponsored by the Southern California Association of Governments (SCAG) and the University of Southern California.

The 32nd annual Demographic Workshop, held virtually this year, is built around the theme, “The Post-Pandemic City,” and takes a close look at several intersecting developments that could significantly change life in the six-county SCAG region. These include the pandemic and post-pandemic recovery, heightened awareness of racial equity and inclusion, and results of the 2020 Census. The latter already will result in California losing a Congressional seat.

Part 2 of the workshop will be held next Tuesday, June 15.

For decades, Southern California has ranked among the most vibrant population centers in the United States, climbing above 19 million. However, the rate of growth has slowed throughout the 2010s as declining fertility rates, the housing crisis and other factors have resulted in a gradually aging — and less mobile — population base.

According to projections released Tuesday, the fastest-growing segment of the population will be mature retirees, ages 75 to 84, followed by young retirees (65 to 74) and seniors (85 and older).

Meanwhile, there will actually be a decline in college-age young adults and preschool-age children. Also, the ratio of working-age adults to retirement-age adults — which once stood at 6 to 1 — has fallen below 4 to 1.

Compounding all of this is the pandemic, which led to an increase in mortality rates, a further decrease in birth rates and virtually halted foreign immigration into California. As a result, 2020 saw the first year-over-year drop in overall population.

“We’re facing a lot of unknowns as we emerge from the pandemic. However, with uncertainty, there is opportunity in front of us,” said Clint Lorimore, president of SCAG and an Eastvale City Councilman.

“It’s a great privilege for SCAG to be able to bring together the best minds across the region and the state so that we can help cities meet their needs and work toward a better future for their residents.”