Thirty years ago last month, Congress replaced the open-ended Aid to Families with Dependent Children (AFDC) entitlement, the largest state-run, federally funded cash welfare program, with the Temporary Assistance for Needy Families (TANF) block grant. This imposed stricter fiscal discipline on states running TANF, but Congress failed to extend similar restraints to other programs. Consequently, many states circumvented TANF’s budget constraints by shifting spending and enrollment to other, still open-ended entitlements. Following the 1996 welfare reforms, states moved some recipients off TANF and onto the Supplemental Security Income (SSI) program. Today, state legislators are shifting costs onto federal taxpayers by...