White Oak Bayou is a slow-moving river in Houston, Texas. A major tributary of the city's principal waterway, Buffalo Bayou, White Oak originates near the intersection of Texas State Highway 6 and U.S. Highway 290 (the Northwest Freeway) and meanders southeast for 25 miles (40 km) until it joins Buffalo Bayou in Downtown. The river serves as a greenway which connects Downtown to the Houston Heights, Oak Forest, Garden Oaks, and Inwood Forest.