The authors examine an important, but understudied, aspect of American political parties: the local organizations that are responsible for increasing the party's community visibility, recruiting first-time candidates, and providing the crucial labor that campaigns use to mobilize voters. They argue that despite overseeing small geographies, the leaders of these local parties wield significant power in American politics to shape statewide and federal campaigns. The book also merges a number of data sources - including national surveys and interviews with party leaders - to describe how local party units impact American politics.