State Policy Innovation and Diffusion (SPID) Database v1.0

The SPID data includes information on the year of adoption for over 700 policies in the American states. For each policy we document the year of first adoption for each state. Adoption dates range from 1691 to 2017 and includes all fifty states. Policies are adopted by anywhere from 1 to 50 states, with an average of 24 adoptions. The data were assembled from a variety of sources, including academic publications and policy advocacy/information groups. Policies were coded according to the Policy Agendas Project major topic code