this study is a much improved nationwide analysis on the county level and includes review and criticism of past publications: https://papers.ssrn.com/sol3/paper

this study is a much improved nationwide analysis on the county level and includes review and criticism of past publications: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2870189 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2870189