HORRY COUNTY, S.C. (WBTW) — Horry County saw a 30% population growth over the last decade, according to Census data released Thursday.

Horry County saw the most growth between 2010 and 2020 out of any county in South Carolina or North Carolina with the increase of 30.4%, according to the data. The county added 81,738 people since 2010, bringing the 2020 population to 351,029.

Horry County is now the 4th most-populated county in South Carolina, behind Greenville, Richland, and Charleston counties, according to the data. Horry County edges out Spartanburg County by about 23,000 people.

The growth in Horry County is so much that infrastructure can’t keep up with the amount of people moving here. In particular, Highway 90 has seen enough growth that Horry County Council wants to temporarily limit re-zoning in that area until the infrastructure can catch up. Residents in that area are concerned about traffic and flooding as hundreds of homes are proposed in the area.

Florence County was the only other county in the News13 coverage area that saw growth, even though it was minimal, according to the data. Florence County saw a 0.1% growth in population, adding 174 people. Every other county in the area saw a decline in population, with Marion and Dillon counties losing the most people, at about 11% each.

Robeson County in North Carolina lost about 13% of its population, according to the data.

Since 2010, South Carolina has grown by nearly 500,000 people to a total population of 5.1 million in 2020, though it wasn’t enough to add another U.S. House seat. Still, the 10.7% increase makes South Carolina the 10th fastest-growing state as it rises above Alabama to become the 23rd most populous state in the U.S.

Some demographic shifts are taking place as well. Overall, South Carolinians are a little older, with 21.6% of residents under the age of 18 in 2020 compared to 23.4% in 2010.

The two largest racial and ethnic groups in the state, whites and African Americans, both saw their share of the population drop slightly in the past decade. Though whites made up 64.1% of South Carolinians in 2010, they comprised 62.1% as of last year. And 24.8% of South Carolinians were Black in 2020 compared to 27.7% ten years earlier.

State lawmakers have been awaiting Thursday’s full data release before they begin to draw lines for U.S. House, state Senate, state House and local districts, though redistricting hearings are already underway. A Senate committee is wrapping up its meetings, while House lawmakers are gearing up to start their own round of hearings across the state, starting in Myrtle Beach next month.

Legislators taking public testimony as they contemplate how to redraw boundaries have already heard from some rural residents worried that the new districts will diminish their already limited power.

Though historically in South Carolina, rural areas often commanded state politics, the population shift makes the loss of power inevitable, said College of Charleston political scientist Gibbs Knotts.

“It was a long time dominated by the rural areas. That’s just not the case anymore,” Knotts said.

The Associated Press contributed to this report.