Wisconsinites leaned Democratic when they went to the polls last month, voting to re-elect President Barack Obama, choosing Tammy Baldwin to be their new U.S. senator and casting more total votes for Democrats than Republicans in races for Congress and the state Legislature.

But thanks in part to the way that Republicans drew the new congressional and legislative districts for this year’s elections, Republicans will still outnumber Democrats in Wisconsin’s new congressional delegation five to three — and control both houses of the Legislature.

Pennsylvanians also voted to re-elect Obama, elected Democrats to several statewide offices and cast about 83,000 more votes for Democratic congressional candidates than for Republicans. But new maps drawn by Republicans — including for the 7th District outside Philadelphia, a Rorschach-test inkblot of a district snaking through five counties that helped Rep. Patrick Meehan win re-election by adding Republican voters — helped ensure that Republicans will have a 13-to-5 majority in the congressional delegation that the state will send to Washington next month.

Republican-drawn lines also helped Republicans win lopsided majorities in other swing states Obama won: Democratic congressional candidates won nearly half the votes in Virginia but only 27 percent of its seats, and 48 percent of the vote in Ohio but only a quarter of its seats.

Last month’s congressional elections were the first to be held in new districts that were drawn across the country after the once-a-decade process of redistricting, when many state officials, charged with redrawing their district maps to account for population shifts, indulge in carefully calculated partisan cartography aimed at giving their party an edge. Republicans had the upper hand: Thanks to the gains they made in 2010 state-level elections, Republicans controlled the redistricting process in states with 40 percent of the seats in the House, Democrats controlled it in states with 10 percent of the seats, and the rest of the seats were drawn by courts, states with divided governments or commissions.

In the nation as a whole, Democratic candidates for Congress won 1.1 million more votes than Republicans, according to a tally of the popular vote kept by David Wasserman, the House editor of The Cook Political Report. But Republicans maintained their control of the House — making this one of a handful of elections in the last century where the party that won the popular vote for Congress did not win control of the House.

Redistricting may sound esoteric, but it can have an impact on governing at the state and federal levels. It may have played a role in Michigan’s decision to pass anti-union legislation this week, a month after Obama won the state by nine points. Michigan Republicans drew the maps in the last two cycles, and even though Republicans lost some seats last month they were able to keep their majority with 54 percent of the seats in the state’s House of Representatives, while getting just 45 percent of the popular vote. And since redistricting gives many members of Congress less competitive, more politically homogeneous districts, it is often cited as one of the factors exacerbating political polarization — a tension can be seen in the current fiscal debate.

The latest round of redistricting is not the only reason Republicans lost the popular vote but won a majority of House seats, several political scientists and analysts said. Incumbency is a powerful weapon, they noted, and Republicans went into the election with a big majority in the House. A new election process in California pitted some Democrats against one another in the general election. And a number of political scientists pointed to what Jowei Chen, an assistant professor of political science at the University of Michigan, and Jonathan Rodden, a professor of political science at Stanford University, call “unintentional gerrymandering” in a forthcoming paper — the natural geographic patterns that lead many Democrats to choose to live in dense, urban areas with very high concentrations of Democrats, effectively packing themselves into fewer districts.

“Now, more than ever in history, Democrats are clustered in a small number of these urban districts,” Chen said in an interview.

But it is undeniable that redistricting played a role as well. The new lines helped Republicans maintain their control of the House, largely because they were able to add more Republican voters to districts where Republicans won close races in 2010.

Michael P. McDonald, an associate professor of public affairs at George Mason University who has served as a consultant on redistricting for both parties, said there was a reason both parties fight so hard for the power to draw the maps — noting that they were not going to all that trouble “just to draw neutral plans.”

Democrats also drew gerrymandered lines in states where they controlled the process, but had less of an impact overall because they had control in fewer states, said Keesha Gaskins, a senior counsel at the Brennan Center for Justice, which has been studying the impact of redistricting.

In Illinois, where Democrats drew the maps, Republican congressional candidates won 45 percent of the popular vote but only a third of the House seats. And in Maryland, Republicans won 35 percent of the votes but just 13 percent of the seats.

An analysis by the Brennan Center found that the new lines that took effect this year may have changed which party won in at least 25 House districts this year, and that they helped Republicans win a net gain of six more seats than they would have won under the old maps.

One particularly striking finding in their analysis highlights the power that comes with drawing the maps. In states where Republicans controlled the process, it found, their candidates won roughly 53 percent of the vote — and 72 percent of the seats. And in the states where Democrats controlled the process, their candidates won about 56 percent of the vote and 71 percent of the seats.

An analysis by The New York Times of states where courts, commissions or divided governments drew the maps found a much smaller disparity between the share of the popular vote and the number of seats won in Congress. In those states, the analysis found, Democrats won slightly more than half the vote and 56 percent of the seats, while Republicans won 46 percent of the vote and 44 percent of the seats.

A flavor of the politics behind the process in Ohio can be found in the exhibits of a lawsuit that challenged the new districts for state lawmakers. Ohio Republicans — who attended a training session on redistricting with a PowerPoint slide that counseled “Keep it secret, keep it safe” — ran their redistricting operation from a room at a Doubletree Hotel in Columbus that staff members sometimes called “the bunker” in emails. The emails show that the Republicans drawing the maps paid close attention to the percentage of the vote Republicans got in past elections in each district.

Ohio’s Republican-friendly districts for state lawmakers were upheld last month by the Supreme Court of Ohio, which ruled in a four-to-three decision that the state’s Constitution does “not explicitly require political neutrality, or for that matter, politically competitive districts or representational fairness, in the apportionment board’s creation of state legislative districts” as long as the other legal requirements are met.

McDonald, of George Mason University, said redistricting could have ramifications for the country, because as members of Congress are drawn into less-competitive districts, they may have less incentive to compromise. “They’re safe in their districts in the House of Representatives,” he said.
 

© 2012 The New York Times Company