San Jacinto, river, c.130 mi (210 km) long, rising in SE Texas as the West Fork and flowing S to Galveston Bay. Its chief tributary is Buffalo Bayou, and both the bayou and the lower river are used for the Houston ship channel. In 1836, Texans under Sam Houston surprised and defeated a larger force of Mexicans in the final and decisive battle of the Texas Revolution on the San Jacinto near the mouth of Buffalo Bayou. The battlefield, a national historic landmark, is in San Jacinto State Park, which has a monument 570 ft (173 m) high; Apr. 21, San Jacinto Day, is a Texas holiday. The U.S.S. Texas is moored near the park. Dams on tributaries include the Barker Dam (39 ft/12 m high; 14 mi/23 km long; completed 1945) on Buffalo Bayou and Addicks Dam (50 ft/15 m high; 12 mi/19 km long; completed 1948) on South Mayde Creek.