39th Street is a major east–west street in Kansas City, Missouri, running almost 5 miles from State Line Road at the Kansas-Missouri border to Topping Avenue in Kansas City's East Side. It was originally named Rosedale Avenue as it led to the town of Rosedale. It continues west into Kansas as 39th Avenue through The University of Kansas Hospital's Kansas City, Kansas, campus.

Kansas City, Missouri is the largest city in the U.S. state of Missouri by population and area. Most of the city lies within Jackson County, with portions spilling into Clay, Platte, and Cass counties. It is the central city of the Kansas City metropolitan area, which straddles the Missouri–Kansas state line and has a population of 2,392,035. As of the 2020 census, the city had a population of 508,090, making it the 37th most-populous city in the United States, as well as the sixth-most populous city in the Midwest. Kansas City was founded in the 1830s as a port on the Missouri River at its confluence with the Kansas River from the west. On June 1, 1850, the town of Kansas was incorporated; shortly after came the establishment of the Kansas Territory. Confusion between the two ensued, and the name Kansas City was assigned to distinguish them soon after.