Political machines, and the bosses who ran them, are largely a relic of the nineteenth century. A prominent feature in nineteenth-century urban politics, political machines mobilized urban voters by providing services in exchange for voters' support of a party or candidate. Allswang examines four machines and five urban bosses over the course of a century. He argues that efforts to extract a meaningful general theory from the American experience of political machines are difficult given the particularity of each city's history. A city's composition largely determined the character of its political machines. Furthermore, while political machines are often regarded as nondemocratic and corrupt, Allswang discusses the strengths of the urban machine approach'chief among those being its ability to organize voters around specific issues.