The Sabine River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

, 510 miles (820.8 km) long, in the U.S. states of Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 and Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

. In its lower course, it forms part of the boundary between the two states and empties into Sabine Lake

Sabine Lake

200px | thumb | Sabine lake as seen from outer space.Sabine Lake is a salt water estuary on the Texas-Louisiana border. The lake, some long and wide, is formed by the confluence of the Neches River and Sabine River. Through its tidal outlet long, Sabine Pass, Sabine Lake drains some of Texas...

, an estuary

Estuary

An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

 of the Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

. The river formed part of the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

-Mexican

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 international boundary during the early 19th century. The upper reaches of the river flow through the prairie

Prairie

Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...

 country of northeast Texas. Along much of its lower reaches, it flows through pine

Pine

Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...

 forests along the Texas-Louisiana border, and the bayou

Bayou

A bayou is an American term for a body of water typically found in flat, low-lying areas, and can refer either to an extremely slow-moving stream or river , or to a marshy lake or wetland. The name "bayou" can also refer to creeks that see level changes due to tides and hold brackish water which...

 country near the Gulf Coast.