Once every 10 years, when you vote for members of the Legislature, you are probably unaware that you are also voting to choose the people who may draw the lines of the state’s congressional and legislative districts.

Just where the lines are drawn is a matter of high politics, because districts can legally be laid out to favor one party or another.

All states that must redraw congressional district lines usually do it in time for the first election after the federal census is taken. The census provides the population data that must be used to create districts, each containing the same number of people.

Maine has been different, traditionally waiting until the second election after the census and realigning the state legislative districts at the same time. But not this year.

The Republicans, with a slim majority in the Maine House of Representatives, wanted to make sure that they could dominate the process and not run the risk of losing control after the next election. They went to federal court, which agreed with them that there was no good reason for Maine to wait an extra two years.

In many states, a politically neutral body handles redistricting. In a few states, those with only one federal representative, there is no redistricting. In Maine, a bipartisan committee is supposed to make a proposal, which must be passed by a two-thirds vote of the Legislature and approved by the governor, subject to a legislative override.

If the process fails, the decision is made by the state Supreme Judicial Court, presumably on a non-partisan basis. That’s what happened in 2003.

The bipartisan committee must find a way to deal with an 8,669 person population margin of the First Congressional District over the Second. In other words, 4,334 people must be moved from one district to the other.

Districts are supposed to be “compact and contiguous.” As few preexisting political boundaries – county and municipal lines – are to be crossed as possible.

The Democrats proposed moving a single town, Vassalboro, across the line, while the Republicans proposed changing a north-south statewide split into a west-east split.  Based on recent elections, the result would be to make the First District more Democratic and the Second District, now served by Democrat U.S. Rep. Mike Michaud, possibly more likely to elect a Republican.

Nobody is being coy about this. GOP State Chairman Charles Webster said his party wants to redraw the lines in its favor “because that’s how politics works.”

The process began in 1812, when Massachusetts Gov. Elbridge Gerry had legislative districts created to suit his Democratic-Republican Party. One looked so much like a salamander that the process came to be known as gerrymandering.

Oddly shaped districts persist, especially because African-Americans have in recent decades been assured of the right to vote. For example, in strongly conservative South Carolina, one district wanders around to collect black voters, so that no more than one African-American will be elected to Congress. The district includes black urban areas, but avoids white suburbs.

Because Maine has only two congressional districts, there is less room for oddly shaped districts, though each proposal has some odd bends.  But it is estimated that the GOP version of the Second District would pick up 8,700 more registered Republicans. The Democrats worry that Michaud only defeated current Republican Senate President Kevin Raye, a possible future opponent, by about 9,000 votes in 2002.

There are some reasons why the political effect of Maine redistricting may not be as crucial as they seem.

In the 2002 race, Michaud was running for Congress for the first time.  Now he is an incumbent with a well-known record. He serves a district that is considered somewhat conservative, and he is a so-called Blue Dog Democrat, making him more conservative than many of his fellow Democrats. For example, he bucked his party and did not vote for U.S. Rep. Nancy Pelosi to lead the House Democrats this year.

And more Mainers are unaffiliated than either Democratic or Republican, and how this swing block votes may matter more than district party registration.

People move between each census, so the political complexion of a district may change.

In the middle of the last decade, without waiting for a new census, Texas Republicans, who had just gained a legislative majority, carried out a new redistricting that netted five new GOP House members. The U.S. Supreme Court confirmed that states could redistrict in less than 10 years, even for purely political reasons. Could that happen here?

Once the congressional lines are settled, Maine law still requires the 2013 Legislature to redraw state legislative lines. Perhaps, thanks to this year’s controversy, redistricting will be more on voters’ minds next election.

Gordon L. Weil is a contributing writer at the Maine Center for Public Interest Reporting: pinetreewatchdog.org. He is an author and publisher and served as a Maine state agency head. Weil was also a correspondent for the Washington Post and a columnist for the Financial Times. He is a former Harpswell selectman. He may be contacted at weil.gordon@gmail.com.