Kentucky bluegrass was introduced into the present-day United States in the 1600s. Since that time, Kentucky bluegrass has spread throughout the United States and Canada becoming prolific in some areas. In the past century, Kentucky bluegrass has been a presence and often a dominant species in some prairies in the Northern Great Plains. Sometime within the past few decades, Kentucky bluegrass has become the most-common species on the untilled, native prairie sites of much of North and South Dakota. In this article, we hypothesize how Kentucky bluegrass has come to dominate one of the most endangered ecosystems in North America—the prairie—through a historical, ecological, and climatological lens. We urge others to start addressing the invasion of Kentucky bluegrass with both new research and management strategies.