Catholics across Borders examines the evolution of a French-speaking population in Plattsburgh over a century. Contrasting with New England's francophone textile mill centers, Plattsburgh featured interethnic cooperation instead of conflict. The book explores how international events affected French Catholic identity at the local level, drawing from French-language newspapers and Catholic archives. Transnational Catholic migrants from Canada and France played a significant role in shaping local, regional, national, and international history in Plattsburgh and beyond, contributing to the larger narrative of the U.S. immigrant experience. This study provides a historic perspective for understanding the present.