FYI - Dallas, TX to Shreveport, LA is only a 3 hour drive. Dallas, TX to Alexandria, LA is only 4.5 hours per Google maps.
Dallas is the crossroads of 2 of the major drug trafficking routes. Route F (pale green on the map below) is the Interstate 35 corridor south-north from the border at Laredo, TX to Duluth, MN, and passing through TX cities San Antonio, Austin, Waco and Dallas. Route A (lavender on the map) is east-west from Los Angeles to Dallas to Atlanta using I-10 and I-20.
Drug Transportation Corridors - National Drug Threat Assessment 2006