This dissertation is a study of free African American politics, in the cities of Baltimore and Philadelphia, between 1817 and 1863. At the heart of this black politics were efforts to assert the right of free African Americans to citizenship in their native United States. Claims on the ambiguous notion of citizenship were important to free blacks both as a means of improving their own lives and as a way to combat slavery. The dissertation begins with the organized black protest against the founding of the American Colonization Society. The contest over the notion, advanced by the ACS, that free blacks were not truly American, or that they could not ever be citizens in the land of their birth, powerfully shaped the language and tactics of black politics. The dissertation ends with the enlistment of black troops in the Civil War, a development which powerfully shaped subsequent arguments for full black citizenship. It argues that in this period, free African Americans developed a rhetorical language of black nativism, the assertion that birth on American soil and the contribution of one's ancestors to the American nation, had won for African Americans the right to be citizens of the United States. This assertion was made even more resonant by the increasing levels of white immigration during this period; African Americans pointed to the injustice of granting to white immigrants that which was denied to native born blacks. This discourse of nativism served as a means of weaving the fight for black citizenship into the fabric of American politics. The dissertation also argues that the cities of Philadelphia and Baltimore were part of a distinctive borderland where the issues of slavery and black citizenship were particularly explosive, and where free African Americans, therefore, found themselves with significant political leverage.