Census estimates show St. Louis metro adds only a few thousand residents as core areas decline

A region that is nearly flat, with growth shifting to the edges

The St. Louis metropolitan area posted only a modest net gain—on the order of a few thousand residents—in the most recent annual set of federal population estimates, underscoring a pattern of limited overall growth paired with internal reshuffling.

Across the bi-state metro, the estimates show population losses in the City of St. Louis and in several long-established parts of the Missouri and Illinois core, while some outlying counties continue to add residents. The net effect is a region that is largely stable in size, but changing in where people live.

Core jurisdictions show declines in the latest estimates

• The City of St. Louis was estimated at 279,695 residents as of July 1, 2024, down from 301,578 at the 2020 Census.

• St. Louis County, Missouri was estimated at 992,929 residents as of July 1, 2024, below its 2020 Census count of 1,004,125.

• St. Clair County, Illinois was estimated at 251,149 residents as of July 1, 2024, down from 257,400 at the 2020 Census.

Metro East results are mixed, with small gains in some areas

On the Illinois side, the Metro East continues to show mixed results across counties. Monroe County, Illinois was estimated at 34,969 residents as of July 1, 2024—roughly flat compared with 34,962 at the 2020 Census—illustrating how some smaller counties have remained steady even as neighboring core counties trend downward.

How these estimates are built—and why “small change” can still matter

Annual population estimates are produced from a combination of births, deaths, and migration. Even when the net metro change is small, the estimates can reflect sizable two-way movement among counties: households leaving the urban core, others arriving from elsewhere in the U.S., and continued inflows from abroad across many metros.

In a slow-growth metro, a net gain of only a few thousand can mask larger flows in and out of individual counties and cities.

What to watch next

The latest estimates reinforce that the St. Louis region’s population story is increasingly about where growth concentrates rather than whether the metro grows at all. The next release cycles will help clarify whether core declines persist and whether incremental metro gains can be sustained amid changing migration and demographic trends.