Data
The Center for Poverty Research annually updates our state level panel data series covering population, employment, unemployment, welfare, poverty, and politics. The UKCPR National Welfare Data begin in 1980 and the excel file may be downloaded free of charge.
State-by-Year Effective Tax Rates in the AFDC/TANF Program from 1983-2002 are available to the research and policy community. These rates were estimated in my 2007 paper "Making Work Pay" in the Journal of Human Resources.