From the summary:
Funding for housing, health, and social services block grants has fallen significantly over time, an examination of several decades of budget data demonstrates. These data provide a cautionary tale for proposals to merge large numbers of additional programs — especially programs serving families and individuals who are low income or otherwise vulnerable — into block grants, as would occur, for example, under a proposal that House Speaker Paul Ryan made in 2014 to merge 11 low-income programs into a mega-block grant in an unspecified number of states.
Policymakers advancing these proposals often accompany them, as Mr. Ryan did, with assurances that the new block grant would get the same overall amount of funding as currently goes to the individual programs that it would replace. This new analysis of several decades of budget data strongly suggests, however, that even if the funding a new block grant received in its initial year matched the prior funding for the programs merged into the block grant, the initial level likely wouldn’t be sustained. The analysis shows that when social programs are merged into (or created as) broad block grants, funding typically contracts — often sharply — in subsequent years and decades, with the funding reductions growing deeper over time.