The American labor movement stands at a turning point. On the one hand, its ranks have greatly diminished after decades of political and economic pressure. On the other hand, the labor movement now enjoys newfound support in the mass public and the Democratic Party. Both the apparent weakness and sources of strength in the contemporary labor movement can be traced to the public sector. Legislative and judicial attacks on government employee unions have driven recent declines in membership, while mass strikes by red state teachers have helped foster greater public support. What explains the unusual role played by public sector unions in contemporary politics—and what can it tell us about the interplay between political institutions and the labor movement?

These are the timely questions tackled by Alexis Walker in Divided Unions, an important study of the public sector labor movement’s development. As Walker notes, political science scholarship has all too frequently elided public and private sector unions. Yet the development of public sector unions has proceeded largely apart from that of private sector unions. While private sector union strength peaked in the immediate postwar era, public sector unions did not start growing in strength until the 1960s and 1970s, with declines in membership beginning in the early 2000s and accelerating sinc