Here in the very red state of Tennessee, it might not exactly be news that white Southern Democrats are a vanishing breed in Congress and the Senate. But this video analysis from The Economist, which follows the evolution of the white Southern Democrat since President Lyndon B. Johnson's signing of the Civil Rights Act of 1964, is still pretty shocking. Legend has it that after signing the bill, Johnson turned to an aide and said, "We have lost the South for a generation." If it's true, his words were prophetic.
At the time, the 11 former Confederate states had 128 seats in Congress, and 115 of them were white Southern Democrats. Yes, you read that right. Of course, these were a different breed of Democrat, and many of them were pro-segregation. (For example, Strom Thurmond was still a Democrat at the time.) The breakthrough of having non-white Democratic congressmen and representatives accounts for some of the decline, certainly, but the bottom line is that the South is now overwhelmingly Republican. In case you hadn't noticed.
Still, if that's the price Democrats had to pay for the Civil Rights Act of 1964, I'm guessing most of them would say it was worth it.