The Sabine River forms part of the border between Texas and which state?

The Sabine River serves as a natural boundary between Texas and Louisiana, making Louisiana the correct answer. Originating in the eastern part of Texas, the river flows southeast, eventually emptying into the Gulf of Mexico. This geographical feature has historically played a significant role in the region's development, serving not only as a boundary but also as a vital waterway for transportation and commerce.

In terms of the other states mentioned, Oregon, Arkansas, and Mississippi do not share a border with Texas that incorporates the Sabine River. Oregon is located in the Pacific Northwest, far from Texas's borders. Arkansas is bordered by Texas to the north but does not have the Sabine River as a boundary; rather, it has the Red River in that area. Mississippi is located east of Louisiana and also does not share a border with Texas defined by the Sabine River. Thus, the geographical relationship of the Sabine River specifically highlights the border it forms with Louisiana.