Two new flat-backed archipolypodan millipede taxa, Orsadesmus rubecollus n. gen. and sp. and Zanclodesmus willetti n. gen. and sp., are described from the Upper Devonian of Clinton County, Pennsylvania, and Miguasha, Québec, respectively. These new taxa are placed in the new family Zanclodesmidae within the order Archidesmida. Archidesmida have previously only been described from the United Kingdom, and their presence in North America confirms a geographic continuum in the millipede fauna across the Old Red Sandstone Continent during the Devonian.