Bat species are facing increasing threats due to climate change, large-scale changes in vegetation, windpower development, and white-nose syndrome, which make research on changes in bat communities essential for conservation planning in North America. The Seminole bat (Lasiurus seminolus) occurs throughout the southeastern United States, and recent evidence suggests they may be expanding their range in North America. I used museum records, publications, and data derived from mist-net surveys conducted by various individuals and organizations to determine changes in the seasonal and historical range of Seminole bats over the past 48 years across eastern North America. Based on records obtained, Seminole bats spend winter along the Gulf Coast, Carolinas, and southern Arkansas, but migrate as far north as Missouri and Kentucky during the summer maternity season. During the autumn juvenile-dispersal period, Seminole bats undergo widespread, long-distance movements and have been recorded in unexpected locations, including the Caribbean, Wisconsin, and New York. Over the past 48 years, the northern edge of their range has advanced 521 km and the western limit of their range has advanced 185 km, at a rate of approximately 11 km/year northward. These data suggest a recent and rapid shift northward, likely in response to climate change, and an expansion westward possibly due to changes in vegetation communities across historic grassland regions.