"The minority population is both growing and dispersing. Fewer and fewer U.S. Congressional districts are predominantly white."

National Journal reports:

The transformation is coloring both parties. Not surprisingly, given their advantages among minority voters, a higher proportion of Democrats than Republicans represent heavily diverse districts. Slightly more than two-fifths of the 258 House Democrats hold districts that are at least 40 percent nonwhite. Nearly three-fifths of House Democrats represent districts that are least 30 percent nonwhite. Only about one-third of them held districts that diverse in 1993.

The change hasn't affected Republicans as much, but neither has it bypassed them. Seventy-six (43 percent) of the 177 House Republicans still represent districts that are at least four-fifths white. But that's down from nearly three-fourths of House Republicans in 1993. Today exactly one-third (59) of House Republicans hold districts that are at least 30 percent nonwhite, with almost all of them coming from California, as well as Texas, Florida, and other Southern states. That's up from only about 10 percent of Republicans who represented such diverse districts in 1993. READ MORE