I stumbled across this website that show the numbers and percentages of black migrants that left the South for other regions of the U.S. The best mapping i came across and cover 100 years (1900-2000). Also contain the maps of other in migrations that occured in the U.S history as well.
http://depts.washington.edu/moving1/map_black_migration.shtml


If you think you are too small to make a difference, you haven't spend the night with a mosquito.
- African Proverb