Missouri and Illinois saw sharp population gains over the past year, but in Missouri, where more than 60% of the population growth in this decade was attributed to international migration, plummeting immigration numbers could spell trouble.
The two states had another year of growth, along with the Midwest and the country as a whole, according to the vintage 2025 population estimate by the U.S. Census Bureau. The annual population estimates track demographic changes from July 1 to July 1 of the next year.
Overall population growth nationwide slowed due to a historical decline in immigration, which dropped from 2.7 million to 1.3 million from July 2024 to July 2025.
As of July 1, 2025, Missouri gained almost 27,000 residents, bringing the state’s population total to roughly 6.2 million. The gain follows a trend, according to census data that shows the state’s population has grown by roughly 1.9% since 2020.
Only 177 more people were born than died, according to the data. Last year, the state gained about half as many international migrants as the year prior, or roughly 12,600 people.
Demographer and St. Louis University professor Ness Sándoval said that while the state is still seeing growth, if immigration trends continue while birth and death rates hold, the state will start to see large declines over the next two decades.
“It's going to be a state that has more people dying than babies born,” Sándoval said. “It is going to be in a position competing with other states for domestic migrants."
Sándoval said the aging of the state’s population, along with baby boomers dying in larger numbers, will play into the decline. He said the state won’t be able to compete with nearby states for people moving throughout the country, and with immigration rates dropping, population growth will continue to slow.
Illinois saw population gain, adding roughly 16,100 residents over the past year. The state has recently reversed declining population trends, after losing residents consistently in the early 2020s.
The region as a whole saw growth, according to the new data, and was the only one where each state had year-over-year population growth. The region saw an initial population decline in 2021 and only small growth in 2022. That number began to “solidly” grow in 2023. In 2024, 386,231 people moved to the Midwest — that growth slowed to only roughly 240,000 in 2025.
“From July 2024 through June 2025, the Midwest also saw positive net domestic migration for the first time this decade,” said Marc Perry, senior demographer at the Census Bureau. “And while the net domestic migration was a relatively modest 16,000, this is still a notable turnaround from the substantial domestic migration losses in 2021 and 2022 of -175,000 or greater.”
Countrywide, the population grew but at a much slower rate over the past year, adding roughly 1.8 million people. In 2024, 3.2 million were added to the census population count. The bureau points to lower levels of international migration as a major cause of that slowdown.
