Bayou Bartholomew is the longest bayou in the world, meandering approximately 364 miles (586 km) between the U.S. states of Arkansas and Louisiana.

In usage in the Southern United States, a bayou is a body of water typically found in a flat, low-lying area. It may refer to an extremely slow-moving stream, river, marshy lake, wetland, or creek. They typically contain brackish water highly conducive to fish life and plankton. Bayous are commonly found in the Gulf Coast region of the southern United States, especially in the Mississippi River Delta, though they also exist elsewhere.