According to the Handbook of Texas, the East Texas area "may be separated from the rest of Texas roughly by a line extending from the Red River in north central Lamar County southwestward to east central Limestone County and then southeastward to Galveston Bay", though some separate the Gulf Coast area into a separate region.

This area includes all or parts of 49 counties, totaling almost 40,000 square miles (100,000 km2) and a population of almost 6 million. Another popular, somewhat simpler, definition defines East Texas as the region between Interstate 45 as the western border linking Dallas and Houston, the Louisiana border as the eastern border, the Oklahoma border as the northern border, and Galveston Bay shores as the southern border.

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