Big Black River is a river in the U.S. state of Mississippi and a tributary of the Mississippi River. Its origin (33°41′40″N89°07′59″W) is in Webster County near the town of Eupora in the north central part of the state. From there it flows 330 miles (530 km) in a generally southwest direction until it merges with the Mississippi River 25 miles (40 km) south of the city of Vicksburg. It is the major contributor to the Big Black River Basin.