...Republicans now control three-fourths of all the House districts where whites exceed their share of the national population, while Democrats hold three-fourths of the districts where minorities exceed their national population share. Republicans hold just over 70 percent of the districts where there are fewer white college graduates than average, while Democrats hold almost 66 percent of the districts with a greater-than-average proportion of white college graduates.
The structural problem for Democrats is that, because of both partisan gerrymandering and the way the population is distributed, there are significantly more districts in the categories the Republicans dominate than in the ones that favor Democrats. Most important, whites exceed their share of the national population in 259 seats, and Republicans hold fully 196 of those—which puts them on the brink of a congressional majority even before they begin to compete for the more diverse seats. And there are 244 districts where the white share of college graduates lags the national average, and Republicans hold 176 of those. (Most of them overlap with the districts where the number of minorities is also fewer than average.)
“It is very hard to argue that there isn’t a structural Republican advantage in the House, that the sorting of voters along lines of urban versus rural, educated versus non-educated hasn’t netted out favorably for Republicans, given the concentration of Democratic voters in a relative handful of districts,” said Patrick Ruffini, a GOP consultant who specializes in demographic trends.
Overall, Republicans hold 241 House seats and Democrats 194 in the new Congress, meaning Democrats must recapture 24 seats to regain the majority.
Like the stark divisions in the presidential race, these patterns underscore the shifting class and racial basis of each party’s electoral base. From the presidency through lower-ballot races, Republicans rely on a preponderantly white coalition that is strongest among whites without a college degree and those living outside of major metropolitan areas. Democrats depend on a heavily urbanized (and often post-industrial) upstairs-downstairs coalition of minorities, many of them clustered in lower-income inner-city districts. They also rely on more affluent college-educated whites both in cities and inner suburbs.
Tellingly, the analysis found, Democrats hold 30 of the 50 House districts with the highest median income—and 32 of the 50 with the lowest median income. But Republicans crush them by 203 to 132 in the districts in between those two poles.