The River Cities Cup, also known as the Dirty River Derby, is a rivalry between American soccer clubs representing Cincinnati, Ohio and Louisville, Kentucky. From 2016 to 2018, the cities were respectively represented in the second-tier league now known as the USL Championship by FC Cincinnati and Louisville City FC. Both teams played in the Eastern Conference of what was then known as the United Soccer League, and the River Cities Cup was contested solely in regular-season matches between the two sides, with the winner of the regular-season series claiming the cup. After the 2018 season, FC Cincinnati ceased USL operations, with the ownership group having been awarded a Major League Soccer franchise that began play under the FC Cincinnati name in 2019. From that point forward, the rivalry