In the initial assignment of state highways in 1917,
Dallas-Fort Worth and Houston were connected by a branch of
State Highway 2 (SH 2, the
Meridian Highway), which ran via
Waco and
Bryan and continued on to
Galveston. The more direct route followed by US 75 was not initially part of the system between
Richland (connected to Dallas by
SH 14) and
Huntsville (connected to Houston by
SH 19). This Richland–Huntsville cutoff was added by 1919 as
SH 32, and US 75 was assigned to the alignment, as well as
SH 6 north of Dallas, in 1926. The branch of SH 2, which US 75 followed between Houston and Galveston, eventually became part of SH 6, and these numbers were dropped in the 1939 renumbering. 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. However, the highways in and near these cities included some of the first
freeways in the state: the Gulf Freeway (Houston, opened to traffic on October 1, 1948) and the
Central Expressway. When
I-45 was built in the 1960s, its alignment bypassed many of the towns and built-up areas between
Downtown Dallas and
Houston. The bypassed routes retained the US 75 designation until the designation was truncated to Downtown Dallas in 1987. Many of the original alignments continue to exist under other designations. In Dallas, the route followed what is now the
Good Latimer Expressway (formerly
Spur 559) southeast, out of downtown, along
US 175 and south along
SH 310. Near
Ferris,
Trumbull,
Palmer,
Ennis, and
Corsicana I-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: •
I-45 Business-J (originally
Loop 560) through
Ferris •
Loop 561 through
Trumbull •
I-45 Business-H through
Palmer (originally
Loop 562) •
Spur 469,
I-45 Business-G (originally
US 287 and
Spur 563) through
Ennis •
Interstate 45 Business-F (originally
Loop 564) through
Corsicana Through
Streetman,
Fairfield,
Buffalo,
Centerville,
Madisonville,
Huntsville,
New Waverly,
Willis, and
Conroe, US 75 followed what is now
SH 75. In Galveston, the alignment of
SH 87 from 20th Street to the southern terminus of I-45 was also part of US 75 until its 1987 truncation. In other cases alignments were bypassed while US 75 remained in existence; they now carry the following designations: •
SH 3 through
La Marque,
Dickinson,
League City,
South Houston and
Houston, bypassed 1952 •
SH 5 from north of
Dallas via
Plano,
McKinney,
Anna and
Van Alstyne to
Howe, bypassed 1959-1967 •
SH 91 from
Sherman to
Denison, bypassed 1984 ==Route description==