Nationally, Obama received nearly 5 million more votes than Republican Mitt Romney. But in some states, large numbers of Obama's votes were packed into heavily Democratic congressional districts. As a result, Romney won 17 more House districts than Obama.
Ohio, Michigan, Pennsylvania, Virginia, Wisconsin and Florida accounted for the entire disparity. Obama won the statewide vote, but Romney won the most congressional districts in each state.
Republicans engineered these disparities by packing large numbers of Democrats into relatively few districts. This resulted in lopsided Democratic districts. For example, Obama won more than 80 percent of the vote in 26 House districts spread across 10 states.
Republican voters were spread more evenly. As a result, Romney won more than 80 percent of the vote in just a single House district, in the Texas panhandle.
Lopsided districts help explain why Congress is so polarized. The divide is reflected in demographic differences, which can shape the debate on a variety of issues.
— Immigration. The average Democratic district has about twice as many Hispanic residents as the typical Republican district. This helps explain why House Republicans have less incentive to pass an immigration bill that would provide a path to citizenship for millions of people living in the U.S. illegally.
— Minimum wage. Democrats represent the vast majority of districts with large pockets of low-income workers and families living in poverty. That helps explain why Democrats are more eager than Republicans to raise the minimum wage. Interestingly, Democrats also represent most of the wealthiest districts, along the East and West Coasts.
— Health care. Democrats represent the vast majority of districts with high concentrations of people who had no health insurance before Obama's new health law, one of many reasons Democrats and Republicans view the law so differently.