Americans have been fighting over how to create congressional districts since 1789.

　　That was when James Madison was elected to the House of Representatives although his Virginia district was created to give his opponent the advantage. Madison went on to become president of the United States, as did his opponent in that election, James Monroe.

　　On Tuesday, the U.S. Supreme Court released a decision in the latest congressional redistricting dispute.

　　Redistricting is the process of redefining congressional districts on a map. Voters within each district elect a representative to the U.S. Congress.

　　The court rejected two congressional districts in the state of North Carolina. The court said race played too large a part in how the districts were created.

　　More African-American voters were added to both districts, making them majority black. Those disputing the redistricting said the result weakened black voting strength in other parts of North Carolina.

　　It happens every 10 years

　　Every 10 years the U.S. government carries out a census that counts the number of people living in all 50 states.

　　After the census, each state develops new district lines for the House of Representatives, and state legislatures, to reflect the new population numbers.

　　Common Cause is an activist group that supports measures to have independent commissions create districts.

　　That would be a change from the current system. Most states now permit the political party that controls state government to create district lines. That gives the majority party's candidates an advantage, according to Common Cause.

　　There are now more state governments controlled by Republicans than Democrats. The Brennan Center, a democracy and justice group in New York, says this has given Republicans an advantage.

　　The group says the benefits provided Republicans are worth 16-17 seats to the current Republican majority in the 435-member House of Representatives.

　　Like a salamander

　　Developing district lines to give one political party an advantage is known as gerrymandering. That term was created in 1812 to make fun of a congressional district, approved by Massachusetts Governor Elbridge Gerry.

　　Some said the 1812 Massachusetts district looked like a salamander, a lizard-like animal that lives in water and on land.

　　Supreme Court Justice Elaine Kagan wrote the recent decision in the North Carolina redistricting case. She said states cannot make race a primary reason for creating district lines, as she said was the case in North Carolina.

　　Republicans, who controlled the redistricting process in North Carolina, said they were guided by politics, not race.

　　Their goal, Republicans said in a legal paper, was to make strong Democratic districts "even stronger" so Republican candidates in nearby districts would do better.

　　The Supreme Court may take up the question of how much politics can affect redistricting next year, said Justin Levitt. He is a law professor at Loyola Law School in Los Angeles, California.

　　"There's no other major Western democracy that lets incumbents draw their own district lines, as we do, and that's the source of a lot of the problems we encounter," he said.

　　The Brennan Center for Justice said six states use independent commissions to create district lines. But most others let state legislators and governors create districts.

　　Eric Holder is the former attorney general under President Barack Obama. He is now the leader of the National Democratic Redistricting Committee, which backed the legal challenge that led to Tuesday's Supreme Court decision.

　　"North Carolina's maps were among the worst racial gerrymanders in the nation,'' Holder said.

　　Robin Hayes is chairman of the North Carolina Republican Party.

　　Hayes complained that it is difficult for legislatures to create district lines, when courts "constantly" change rules "from case to case, often after the fact."

　　The Supreme Court ruling criticized how North Carolina creates districts. But the two districts considered by the court were already changed, as a result of earlier court rulings.

　　More and larger congressional districts

　　The size of House of Representative districts has grown as America's population has increased.

　　In 1790, each of the 110 members of the House of Representatives represented about 34,000 residents. Today, there are 435 House members, with districts of about 711,000 people each.

　　Congress is divided into two bodies -- the House of Representatives and the Senate. The number of House members in each state is based on population.

　　In the Senate, each state has two senators, regardless of population. So California, with a population of 39.2 million, has the same number of senators as Wyoming, with about 585,000 residents.

　　I'm Jill Robbins. And I'm Bruce Alpert.

　　Bruce Alpert reported on this story for VOA Learning English. Mario Ritter was the editor.

　　We want to hear from you. Write to us in the Comments Section and share your views on 51VOA.COM.