The modern American agricultural fair, an annual harvest-time celebration at which livestock, produce, and handicrafts are exhibited for premiums, originated as an innovative response to conditions in rural New England at the time of the War of 1812. This study explains the birth of the institution by scrutinizing the motives and methods of its founders. In particular, it traces the intellectual journey from Puritan youth to Jeffersonian promoter of Plymouth, Massachusetts, native Elkanah Watson (1758--1842), its chief publicist. This dissertation also examines the specific social, economic, and political forces that shaped Pittsfield, Massachusetts---to which he retired from a mercantile career in Albany, New York, in 1807---leading to the formation of the Berkshire County Agricultural Society in 1811, which organized America\u27s first successful county fairs. Inspired by a vision of a United States no longer dependent on Great Britain for its cloth, Watson and the new local elite---professional men and capitalist entrepreneurs---imported fine-fleeced Spanish Merino sheep and established the first woolen factories in Pittsfield. their new type of agricultural society would hold annual fairs for farm families to promote both, as well as to introduce agricultural improvements in general. In addition to being a popular institution of agricultural education, the fair was one of self-improvement. Answering deep needs of the rural community, it aimed to replace undisciplined folkways with secular ritual, healthy competition, rational amusements, and innocent recreations. The origins of the agricultural fair can best be understood in its synergistic relationship with the new forces sweeping the country in the era of the early American republic: the capitalist transformation of the countryside, the early development of American manufactures, the democratization of American society and politics, the secularization of moral reform, the rise of voluntary associations, the heightened significance of the social sphere (especially for women), and the growing importance of public festivity. The fair assumed today\u27s form, with spectacles, sports, and Midway entertainments competing with agricultural exhibitions, only after railroads came to towns like Pittsfield around the mid-nineteenth century, intensifying the pace of socioeconomic change and bringing many more nonagricultural participants to the fairs