Prior to the coming of the Interstate Highway System in the late 1950s, the only improvements to US 75 in Texas beyond building a two-lane paved roadway were in the Houston and Dallas areas.

In Dallas, the route followed what is now the Good Latimer Expressway (formerly Spur 559)[6] southeast, out of downtown, along US 175 and south along SH 310.

[7] Near Ferris, Trumbull, Palmer, Ennis, and Corsicana Interstate 45 veers east to avoid the more populated areas.

The old US 75 alignments through these towns, decommissioned in 1987, now carry the following designations: Through Streetman, Fairfield, Buffalo, Centerville, Madisonville, Huntsville, New Waverly, Willis, and Conroe, US 75 followed what is now SH 75.

[14] In other cases alignments were bypassed while US 75 remained in existence; they now carry the following designations: US 75 begins at I-345, an unsigned auxiliary route of I-45 and heads north, first interchanging Spur 366 northeast of Dallas.