Dynamics of Economic Well-Being: Poverty 2009-2012
http://www.census.gov/hhes/www/poverty/publications/dynamics09_12/index.html
A set of 8 tables which traces a sample of U.S. residents and examines how many of them were poor during at least some portion of the sample time period. Also looks at length of poverty duration, entrance to and exit from poverty and how many stayed poor throughout the period. From the Census Bureau