Americans today worry about concentrated power in private industry to an extent not seen in generations. Not only do they find diminished diversity of service-providers and producers, but they are disquieted by the power of a few large companies to shape and constrain democratic processes. Americans across the political spectrum, from former President Donald Trump to Massachusetts Senator Elizabeth Warren, have sounded alarms about the overlarge power of business in both public and private life. While many of the technologies and industries that worry Americans are new, the concerns they've raised are not unprecedented.Antimonopoly and American Democracy traces the history of antimonopoly politics in the United States, arguing that organized action against concentrated economic power comprises an important American democratic tradition. While prevailing narratives tend to treat monopoly as a risk to people mainly in their roles as consumers--by causing prices to increase, for example--this study broadens the conversation, recounting ways in which monopolism can hurt ordinary people without directly impacting their wallets. From the pre-revolutionary era to the age of Big Tech, the volume explores the effects that historical monopolies have had on democracy by using their wealth and influence to dominate electoral politics and regulation. Chapters also highlight a range of sites of economic concentration, from land ownership to media reach, and attempts at combating them, from labor organizing to constitutional revision. Featuring original scholarship from some of the world's leading experts in American economic, political, and legal history, Antimonopoly and American Democracy offers important lessons for our contemporary political moment, in which fears of concentrated wealth and influence are again on the rise.