Check out this week's data visualization from the U.S. Census Bureau, which looks at The Great Migration of the Black population from 1910 to 1970, when an estimated 6 million people left the South for urban centers in other parts of the country. http://www.census.gov/dataviz/visualizations/020/ [1]
Links:
[1] http://www.census.gov/dataviz/visualizations/020/
[2] http://www.library.uni.edu/category/tags/census
[3] http://www.library.uni.edu/category/tags/cornerstone
[4] http://www.library.uni.edu/category/tags/data
[5] http://www.library.uni.edu/category/tags/news
[6] http://www.library.uni.edu/category/news/government-documents-news