Members of the genus Cryptocercus are subsocial, xylophagous cockroaches that inhabit temperate forests of the Nearctic and Palaearctic. Seven species are recognized worldwide: five in the United States, and one each in Russia and China. Four (Cryptocercus darwini Burnside, Smith and Kambhampati, Cryptocercus garciai Burnside, Smith and Kambhampati, Cryptocercus punctulatus Scudder, Cryptocercus wrighti Burnside, Smith and Kambhampati) of the five species in the United States occur in the Appalachian Mountains and one (Cryptocercus clevelandi Byers) occurs in the Pacific Northwest. Previous studies have indicated that the distribution of the Appalachian species is allopatric; however, three of the four species occurred within a few kilometers of one another. Therefore, an intensive survey was undertaken in southwestern North Carolina and northern Georgia to determine if the species distributions are indeed allopatric or if there are zones of sympatry. With regard to C. clevelandi, previous studies have included samples from only a handful of locations in the western United States. Therefore, an extensive survey was undertaken in Oregon and California to map the geographic distribution of C. clevelandi and estimate genetic variation within and among populations. Our surveys indicated that three (C. darwini, C. garciai, C. wrighti) of the four Appalachian species have overlapping distributions in southwestern North Carolina and northern Georgia, a finding that raises the possibility of the existence of hybrid zones. Genetic variation among samples collected in Oregon and California indicated that, unlike the eastern United States, there is only one species of Cryptocercus in the western United States. In addition, we found that the distribution of C. clevelandi is considerably more patchy than that of the Appalachian species.