A Houston “Yes! to Census 2020” mural on the side of SHAPE Community Center in 3rd Ward in June 2020. Photo courtesy 'Yes! To the Census 2020.'

Harris County grew by 15.6% since 2010, with a bulk of that population increase occurring outside of Houston, according to census data released Thursday.

More than 4.7 million people now live in Harris County, up from around 4 million in 2010. That’s more than the population of Chicago, America’s third-largest city. Houston’s population percentage increase was second only to Phoenix among the top 10 big cities in the U.S.

The adult population of Harris County grew by 19.5% since 2010, to about 3.5 million.

Houston remains the fourth-largest city in the country, and its population growth lagged the county as a whole. Between 2010 and 2020, the city’s population grew just 9.8%, to about 2.3 million.

The statewide population outpaced both Houston and Harris County, growing about 16% to more than 29 million in 2020.

The latest census data will be used by lawmakers to draw new congressional and state legislative maps in an upcoming special session. But it’s not clear if that process will get done in time for next year’s primaries, thanks to a pandemic delays and multiple special sessions ahead of redistricting.

Houston and Harris County spent an unprecedented $5.1 million in total to boost outreach for the 2020 census, fearing a population undercount. But that investment was likely hurt by the COVID-19 pandemic, leading to fears that harder-to-count communities that include immigrants and refugees.

Houston Mayor Sylvester Turner said the city would review the census data.

“It is vitally important that we achieve an accurate count to ensure that Houstonians receive the representation and public resources our City deserves and needs for the next decade,” read a statement from the mayor’s office.