river in the southwestern United States, rising in northeastern Texas and flowing southeast and south, broadening near its mouth to form Sabine Lake, and continuing from Port Arthur through Sabine Pass, a dredged navigable channel, to the Gulf of Mexico after a course of 578 mi (930 km). It drains 10,400 sq mi (26,950 sq km), entirely in Texas and the Louisiana Coastal Plain. The Sabine has successively served as a boundary between the territories of France, Spain, the United States, and Mexico, and between Texas and Louisiana. The Sabine-Neches Waterway, a portion of the Gulf Intracoastal Waterway, provides 52 mi of deep waterway through Sabine Pass, along western Sabine Lake and the lower Neches River to Beaumont, Tex., and 44 mi of deep waterway to Orange, Tex., 10 mi north of the mouth of the Sabine. The river's original name, Sabinas, the Spanish name for the red cedars growing on its banks, was changed by French-speaking people to its present form.