Writing for National Journal, political analyst Ronald Brownstein looks at the degree to which the two major parties are divided by race. Hint - it's a lot.
Ron begins by pointing out that the GOP cannot keep winning presidential elections without minority votes, probably from Asians and Hispanics. Once he has you convinced that the Dems are going to win, then he turns around and points out that they won't be able to control Congress without white votes.
Brownstein's bottom line is that both parties need to figure out how to appeal across racial lines. To date, neither party has broken that code.
In this early part of the 21st century, the two parties reflect a racial division. Read Brownstein's article, it's a good one.