This paper considers the role of colonial history and colonial archives in the formation of early national history in the United-States, through a comparison between the Massachusetts Historical Society founded in 1791, and the New York Historical Society, created in 1804. While the New York Society struggled financially to build its colonial archive and to publish it, the Boston institution enjoyed the fruits of a private archive, itself a product of the promotional dimension of colonization and of the institutional requirements of permanent settlement. Settlement also shaped the political outlook of its members, who embraced expansion as the engine of the American enterprise of colonization. When history became professionalized in the late 1880s, and historiography began to look back on the past century for a tradition of scientific history serving the common national interest, the archival and analytical practices of the MHS came again to the fore, attesting to the role of political colonial sources in shaping wide historical interpretations of the meaning of American expansion.