WASHINGTON — How many candidates does it take to make six congressional races competitive in South Carolina?

More than 13, apparently.

All but one of the five U.S. House incumbents who will seek re-election Tuesday has at least one challenger. And in the one open seat — the Upstate’s 4th District — three people are running.

But those who know S.C. politics say they can tell right now who is going to Washington after Tuesday’s election — the incumbents: Henry Brown, Jim Clyburn, John Spratt, Joe Wilson and Gresham Barrett, who is unopposed.

That lack of competition is “counterproductive to a democratic society,” College of Charleston political science professor Bill Moore said.

Even in the lone race without an incumbent — the 4th District, which includes Greenville and Spartanburg — political scientists say the GOP candidate is so heavily favored in the Republican-dominated district that he might as well be the incumbent.

He once was. After three terms in Congress, Bob Inglis ran unsuccessfully for the U.S. Senate against Democrat Fritz Hollings six years ago. Inglis lost but now is hoping to reclaim the House seat, being vacated by U.S. Rep. Jim DeMint, R-Greenville, who is running for the U.S. Senate.

Political observers bemoan the reality that, nationwide, more than 95 percent of incumbent U.S. House members win re-election every two years. Some years it is as high as 98 percent.

“The incumbents are winning not necessarily because they’re doing an outstanding job,” Moore said, “but because the districts are so badly gerrymandered that a challenger can’t win.”

To “gerrymander” is to create a legislative district to benefit a particular party. It is named after Elbridge Gerry, a colonial governor of Massachusetts, who, ironically, spoke out against the practice.

“In virtually every state, it’s left to partisan forces to design the electoral district,” said Winthrop University political science professor Scott Huffmon. “They get to design safe districts for their party.”

In South Carolina, and in nearly every state, a committee of state legislators draws the lines for both legislative and congressional districts.

Huffmon said that process creates two bad results:

• Groups within the districts will never get to vote for a candidate they feel represents them.

• Entrenched politicians feel little need to compromise or to defend their policy choices as better than an alternative.

Even politicians who benefit from the system aren’t necessarily comfortable with it.

U.S. Rep. Wilson, R-S.C., won a special election for his 2nd District seat in 2001 and his first full term in 2002 with 84 percent of the vote.

“I have mixed feelings,” said Wilson. He noted a majority of state legislatures are in Republican hands. “They are the people who draw the districts lines. I’m happy the Republicans are winning.

“I am concerned that a long-term gerrymandering could be unhealthy in terms of checks and balances.”

Wilson’s campaign coffers reflect an incumbent’s advantage.

He has raised $795,107 this election season, according to the Federal Election Commission. His Democratic challenger, Lexington attorney Michael Ray Ellisor, had raised $8,212 by June 30, the latest date for which figures for him are available.

Reach Markoe at (202) 383-6023 or lmarkoe@krwashington.com