Although the aggregate growth rate of the American economy was relatively slow between the Revolution and 1840, certain sectors did expand at a rapid rate, and from these sectors originated some of the factors responsible for the later dynamic growth of the whole system. One such sector involved the making of clocks. Never large by any measure, the clock industry was, nevertheless, a leader in the introduction of the system of interchangeable parts production and in the mass marketing of a “luxury” consumer good. The purpose of this article is to outline and to analyze the transformation of this activity from a craft to an industry and, in particular, to indicate the factors which influenced Eli Terry, the main entrepreneur of the transformation.