The most significant long-term political consequences of Tuesday's elections have nothing to do with GOP House or Senate gains. What matters for the shape of politics over the next decade is that Republicans will hold more seats in the 50 state legislatures than at any time since before the Great Depression.
That's because once the census results are in next year, most state legislatures will redraw the district lines for Congress and their own legislative bodies (usually subject to a veto from the governor). "The GOP, in dramatic fashion, finds itself now in the best position for both congressional and legislative line-drawing than it has enjoyed in the modern era," says Tim Storey, elections specialist at the National Conference of State Legislatures. The GOP will control the governorship and both legislative bodies necessary to dictate new maps in 17 states including Alabama, Indiana, Maine, Michigan, North Carolina, Ohio, Pennsylvania and Wisconsin.
As recently as the 1990 Census, Republicans enjoyed such total control in only two states with five House seats. In this cycle, Republicans will control the drawing of at least 195 districts. Assuming Republicans prevail in recounts and recapture control of the New York State Senate, Democrats will have total control of the process in 65 seats. The parties will share control in the drawing of another 86 seats. Eighty-eight seats will be drawn by commissions in six states.
Where the number of House seats will rise or fall due to population shifts, Republicans will control the process in key states that gain seats, such as Texas (plus four), and that lose seats, such as Ohio (minus two). Given that Republicans will control the redrawing of 40 of the country's 70 most competitive House seats, look for a couple Democratic incumbents—possibly North Carolina's Mike McIntyre—to contemplate switching parties to ensure they get districts they can survive in.
The raw use of power to draw districts that benefit one party over another—called gerrymandering—is as old as our republic and has been upheld by the Supreme Court on several occasions. But at its core it allows incumbents to pick their voters, rather than having voters pick their representatives.
Gerrymandering creates bizarre and serpentine districts that pack members of an opposing political party into as few districts as possible while leaving the rest dominated by the party drawing the lines. The 2000 gerrymander of California by Democrats was a spectacular case. Only nine of the state's 865 legislative and congressional elections held in the years since have seen a switch in party control.
Several states—including Arizona, Iowa and Washington state—have curbed the gerrymander by having independent bodies draw district lines that are compact, contiguous and don't arbitrarily violate city and county boundaries. Voters are clearly warming to the idea. This week, 61% of Californians voted to place redistricting authority for the state's congressional districts with a 14-member citizen commission. Rep. Nancy Pelosi (D., Calif.) fiercely opposed the measure and helped place a competing proposal on the ballot to take away the commission's existing authority to draw state legislative lines and return it to the legislature. Her measure won only 40%, losing every county save her hometown, San Francisco.
In addition, this week 62% of Florida voters passed their own redistricting reform requiring that voting districts follow objective criteria for compactness and contiguity. Doug Schoen, a Democratic pollster who did polling on the measure, told me, "People are catching on that gerrymandering restricts their choices and are looking for a better way."
But Democrats worried about the impact of the new GOP redistricting muscle will do more than belatedly call for good-government alternatives. Look for them to encourage the Obama Justice Department to slow-walk or block redistricting plans submitted to it by the 14 states covered in whole or in part by the Voting Rights Act. This law requires those states to "preclear" their new maps with either the Justice Department or the U.S. District Court for the District of Columbia. States denied preclearance often see their maps eventually being drawn by federal judges.
The ugly legal battles and lengthy delays likely to result from next year's redistricting could lead voters to demand that elected officials have less power in the process. While there's no way to take politics entirely out of redistricting, its influence can be limited. Until then, look for Democrats—frequent abusers of the gerrymander after past censuses—to stir up public outrage over Republican abuses (real or imagined) of their newfound district-drawing duties.
Mr. Fund is a columnist for WSJ.com.