This dissertation explores the elaboration of “conservative” thought in the United States from its genesis in eighteenth-century transnational moral philosophy and bio-medical research to its expression in national conflicts over race and slavery, empire and expansion, immigration and naturalization, and free trade and market capitalism from the 1820s through the 1850s. Looking at competing groups of public intellectuals, politicians, activists, radicals, and religious leaders who defined themselves or their positions as “conservative” in the nineteenth-century United States, it argues that American “conservatives” developed a radically adaptive system of meaning that can only be understood within the contemporaneous development of conservative schema internationally. This intervention connects American conservatism to the organismic ontology of the state as a naturally progressing, living system, with its hybrid philosophical genesis in British sentimental theory and continental theories of organic generation and reproduction. The contest to represent the “true conservatism” of the country reflected a struggle over the nature of the United States as an organically unified society with a system of laws, government, and behavior that naturally developed to suit that society. This long history of conservatism establishes the integral link between historical conservatism and contemporary racial nationalism and opens up an avenue for inquiry into the role that biology played in shaping America’s socio-political imaginary and its political and institutional genealogy.