What if welfare had no work requirements? the age of youngest child exemption and the rise in employment of single mothers

"The Personal Responsibility and Work Opportunity Reconciliation Act of 1996 required states to increase welfare recipient employment and participation in welfare-to-work programs. These work requirements are sometimes credited for bringing about large employment increases among single mothers. However, this paper finds that employment among single mothers who were exempted from work requirements because they had young children rose as much as that of other single mothers. The results imply that the employment gains among single mothers in the late 1990s were due to economic growth and other policy changes rather than to the work requirements"--Federal Reserve Board web site.