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 Mr. 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.