MARSHALL — The population of Lyon County and the city of Marshall both shrank over the past 10 years, although not as much in Marshall, according to U.S. census data released Thursday.

Lyon County had a population of 25,259 in the 2020 census, a decrease of 588 people from 2010. Marshall’s census results stayed relatively flat, but were still down — the 2020 census showed a population of 13,628, which was a decrease of 52 people compared to the 2010 count.

“I think we were all uncertain about what the census would be. It happened at a very unusual time in history,” said Marshall Mayor Bob Byrnes.

“In Marshall, the census was taken at a time when the population was moving” due to COVID-19 shutdowns, he said. Having fewer students on campus at Southwest Minnesota State University in April could have been one influence on the city’s census results, he said.

Data released by the U.S. Census Bureau on Thursday showed a more detailed look at population and demographic shifts within each state, including information on individual counties and cities. Figures released earlier this year showed that Minnesota’s population grew to 5.7 million in 2020, an increase of 7.6%, which was just barely enough to let the state keep its eight congressional districts.

Census data showed growth in some southwestern Minnesota cities over the past decade. The population of Worthington grew to 13,947, an increase of more than 1,100 people from 2010. The city of New Ulm grew by almost 600, to a population of 14,120. The city of Willmar had a population of 21,015, an increase of more than 1,400 people from the 2010 census.

Byrnes said it seemed likely that last year’s census counted fewer SMSU students living on campus than normal. Last spring, the university had switched to distance learning due to COVID-19 concerns, and having fewer students living in Marshall would have an impact on the census count, he said.

While it was disappointing to have 52 fewer people in Marshall, Byrnes said there has been a trend of population decreases in rural Minnesota.

In the future, he said, “We will really have to look at where are our strengths,” as well as opportunities for growth in Marshall.

Thursday’s data release also included race, age and other demographic information for Minnesotans in the 2020 census. Minnesota remains overwhelmingly white, though not by as much.

The population identifying as white dipped from 83.1% in 2010 to 76.3% in 2020. But the population identifying as Black rose from 5.1% to 6.9%. Whites remain the largest racial group in every Minnesota county. The state’s most diverse county is Mahnomen, where Native Americans make up 41.7% of the population.

Minnesotans age 18 and older make up 76.9% of the population. The 18-plus population rose 9.2% from 2010 to 2020 while the growth in the under-18 population lagged at 2.6%.

One of the biggest things at stake in the new census numbers is the state’s political map, which must be redrawn to reflect population shifts. The data show a shift away from greater Minnesota toward the Twin Cities area, particularly the suburbs. Redistricting usually ends up in the courts.

Byrnes and Lyon County Auditor/Treasurer E.J. Moberg said the redistricting data will also be important at the local level. Census data is used to determine where Marshall draws the boundaries of its three voting wards. In turn, population data from the Marshall wards has an impact on Lyon County commissioner districts.

If there’s enough population change in county commissioner districts, those seats may have to go up for re-election in 2022, Moberg said.

— The Associated Press contributed to this report