This article recovers Buckinghamshire county council's proposal to build a monorail city for 250,000 residents during the 1960s. The project was eventually taken over by Whitehall, which proceeded to establish Britain's largest new town of Milton Keynes instead, but from 1962 to 1968 local officials pursued their monorail metropolis. By telling the story of ‘North Bucks New City’, the article develops a series of claims. First, the proposal should be understood not as the eccentric creation of a single British county, but rather as one iteration of larger state efforts to manage the densities and distributions of growing populations. Second, while the 1960s witnessed the automobile's decisive triumph as a means of personal mobility in Britain, that very triumph ironically generated critiques of the car and quests for alternatives. Third, the monorail was part of a complex social vision that anticipated – and, in part through the facilitation of recreational shopping, sought to alleviate – a crisis of delinquency expected to result from a world of automation and affluence. Fourth, despite its ‘futuristic’ monorail, the plan ultimately represented an effort by experts and the state to manage social change along congenial lines. Fifth, the proposal advanced a nationalist urbanism, promising renewed global stature for post-imperial Britain by building upon its long urban history. Finally, the article concludes by arguing that this unrealized vision points to the limitations of ‘modernism’ in the history of urban planning, and to the problems of teleology in the history of the 1960s.