Katie Arrington and Joe Cunningham Debate03.jpg (copy)

Democrat Joe Cunningham , left, and Republican Katie Arrington in their first debate in South Carolina’s 1st Congressional District on Tuesday, Oct. 16, 2018 at the Lightsey Chapel Auditorium on the campus of Charleston Southern University. Andrew J. Whitaker/ Staff

South Carolina's largest and wealthiest congressional district — the only one where most residents are not S.C. natives — is about to choose a new representative in a hard-fought contest that's received national attention.

It's a district where the population has been rapidly growing and changing in the greater Charleston area and coastal communities from Hilton Head Island to McClellanville. Whether that changing population will mean a change in political preferences is a question voters could answer Tuesday.

The competitiveness of the contest between Republican Katie Arrington and Democrat Joe Cunningham is unusual because the 1st District was, like all but one of the state's congressional districts, drawn to favor Republican candidates by a comfortable margin. In the last presidential election, Donald Trump carried the 1st District by 13 percentage points, and the 1st hasn't sent a Democrat to Congress since the late 1970s.

Leading political analysts describe the district as "leans Republican," where a Democrat would have to do unusually well just to close the built-in GOP advantage. Forecasters at FiveThirtyEight give Cunningham a less than 10 percent chance of winning, but then, that's more of a chance than CNN projected for Donald Trump the day before the 2016 election.

In South Carolina, the 1st District stands out in several ways.

It's home to some of the most rapidly growing areas on the East Coast, including the Charleston and Hilton Head metro areas. In Bluffton, the population increased 68 percent since 2010, according to Census Bureau estimates.

“You would think that the in-migrants might be more disposed to vote Democrat, or at least less Republican, because they are coming from more Democrat-leaning areas," said DuBose Kapeluck, chairman of the Department of Political Science at The Citadel. "But it seems the people coming here tend to be more Republican than Democrat."

In the greater Charleston area, the 1st District's boundaries exclude large majority-black areas such as North Charleston and the Neck Area, while including high-wealth majority-white areas such as barrier islands, Mount Pleasant, Daniel Island and the Charleston peninsula south of Calhoun Street. The 1st also jogs inland through Summerville and up to Moncks Corner. 

SC 1st Congressional District

As a group, the district's residents are far wealthier than the average South Carolinian.

Median household income in the district, the amount where half have more and half have less, is $66,337. That's nearly $20,000 higher than household median income statewide, and 30 percent of households in the 1st have income of at least $100,000.

Residents of the 1st are also, as a whole, highly educated.

Among adults age 25 and older, half of those in the 1st District have at least an associate's degree and 40 percent have a bachelor's degree or higher. Among the state's seven congressional districts, the 1st has the lowest unemployment rate, the highest median home value and the most residents who described their ancestry to the Census Bureau as "American."

And the district, with more than 782,000 residents and 518,000 registered voters, is full of people "from off."

The area's rapid population growth has been driven by people moving to the Lowcountry from other states, and Northeastern states in particular. The 1st is the state's only congressional district where most residents were, like Arrington and Cunningham, born outside South Carolina.

“The myth about Charleston is that everyone is coming from Ohio and the Midwest," said Jordan Ragusa, political science associate professor at the College of Charleston. "They are coming more from New York and New Jersey."

“If the larger national patterns hold, I think the demographics of the 1st District are changing slowly, in a way that favors Democrats," he said.

The 1st District seat is currently held by Republican former S.C. Gov. Mark Sanford. He's represented the 1st since 2013, and previously from 1995 to 2001, but was defeated in the GOP primary this year.

Arrington, 47, is a first-term state lawmaker who defeated Sanford in the Republican primary partly by highlighting his reluctance to support Trump unconditionally. Cunningham, 36, is a Charleston lawyer and son of a Kentucky Supreme Court justice who is seeking public office for the first time.

Within the 1st District, there are important differences from county to county.

Fast-growing Beaufort County, with more than one fifth of the 1st District's registered voters, is home to the retiree havens of Hilton Head and Bluffton, and nearly 42 percent of 1st District registered voters there are 65 or older — roughly double the percentage in the district's other counties. The county, full of elderly newcomers, was a stronghold for Arrington in the primary election. 

Charleston County is home to 41 percent of potential voters in the 1st. It was one of two counties in the state that didn't vote for Trump in the Republican presidential primary, choosing Sen. Marco Rubio instead along with Richland County, but the 1st District excludes many Democrat-heavy parts of the county.

Like Berkeley and Dorchester counties, more than four out of 10 1st District voters in Charleston County are age 25 to 44.

In the 2018 Republican primary won by Arrington, she collected more votes than Sanford in the Dorchester, Berkeley and Beaufort county portions of the district, while Sanford received more votes in Charleston County and the small slice of Colleton County — Edisto Beach — within the district.

“My impression is that the 1st District is more libertarian and less socially conservative," Kapeluck said. “He (Sanford) was pretty representative of the district.”

Many coastal areas in the district are majority Republican but also oppose offshore oil exploration and are willing to pass regulations aimed at protecting the environment.

Consider Mount Pleasant, an affluent town of about 87,000 in the 1st. The town is governed by Republicans but has moved aggressively to restrict development, and this year approved a sweeping ban on plastic bags and polystyrene packaging such as take-out containers.

“There are some interesting regional patterns in South Carolina," Ragusa said. "You’ve got the God and guns voters in the Upstate, a lot of veterans and establishment Republicans in the Midlands, and in the Lowcountry it's more fiscally conservative and Libertarian."

The 1st District is full of new residents, and the district boundaries have changed over time because congressional districts are redrawn after each decennial census to account for population changes. The 1st included much of Horry County (home to Myrtle Beach to the north) previously, but its boundaries were shifted down the coast, excluding Horry County and adding Beaufort County in 2011.

Despite the changes, one thing has stayed the same for decades — the political party 1st District voters have chosen to represent them in the U.S. House. No Democrat has won the 1st since the late 1970s, when Mendel Davis held the seat.

The closest a Democrat has come to winning that seat in Congress in recent years was in 2008, when incumbent Republican Henry Brown defeated challenger Linda Ketner by just 4 percentage points. In 2013 in a special election, after then-incumbent Rep. Tim Scott went to the U.S. Senate, Sanford easily won the 1st despite the lingering "Appalachian Trail" scandal from his affair while governor.

Reach David Slade at 843-937-5552. Follow him on Twitter @DSladeNews.

David Slade is a senior Post and Courier reporter. His work has been honored nationally by Society of Professional Journalists, American Society of Newspaper Editors, Scripps foundation and others. Reach him at 843-937-5552 or dslade@postandcourier.com