Wisconsin’s Rebecca Blank and Michigan’s Brian Kovak (now at Carnegie Mellon) find that the share of single mothers with no earnings or welfare and not in school doubled from 10 to 20 percent from 1990 to 2005. If you include women with very low earnings and no SSI income, the rate goes from 12 to 22 percent. As work requirements spread, mothers who couldn’t find work lost benefits and were left getting by with nothing.