SH 46 was originally designated on October 20, 1919 as a route from
New Braunfels north to
Johnson City. On July 13, 1925, the route had been shortened, with the section north of
Spring Branch transferred to
SH 108. This alignment of SH 46 only consisted of the portion from
US 281 to
US 81 in New Braunfels. On July 16, 1928, it was extended to
Seguin. On July 15, 1935, the section from New Braunfels to Seguin was cancelled. On October 26, 1967, the highway was relocated in New Braunfels to the east along the alignment of
Loop 337, but still had an eastern terminus at US 81. On June 21, 1990, the designation of this segment was officially changed to Business 46. On October 28, 1960, SH 46 was signed, but not designated, over
Farm to Market Road 25 from I-35 to
US 90 and
Ranch to Market Road 475 from US 281 to
SH 16. On June 30, 1961, the section of FM 25 from FM 78 to US 90 became part of the new
Spur 351. On February 26, 1968,
SH 46 was officially extended to the south from US 81 to I-35, replacing part of FM 25. On September 28, 1988, the highway was officially extended at both ends, extending the eastern end south replacing FM 25 from I-35 to
FM 78 and then replacing part of
Spur 351 from FM 78 to
I-10 in
Seguin. On May 14, 1990, the highway was extended to its current alignment when it was extended south from I-10 to
SH 123 replacing the remainder of
Spur 351. Construction started in fall 2017 and also included reconstruction of existing bridges and interchanges. Construction was completed in May 2021 at an estimated cost of $42.3 million. ==Route description==