Texas State Highway OSR

State Highway OSR (SH OSR) is a state highway in the U.S. state of Texas.

The route is the section of the Old San Antonio Road in east-central Texas that is maintained by the Texas Department of Transportation. While most of the original Old San Antonio Road (that is, the section of the road that is not private property) follows State Highway 21, State Highway OSR provides a routing close to the original alignment of the road near and around the Bryan-College Station metropolitan area.

"OSR" is the only state highway in Texas with a completely alphabetical designation and one of only two where the designation begins with a letter (Texas State Highway NASA Road 1 being the other with a beginning letter).

Route description
OSR begins at an intersection of SH 21 just east of the Brazos River in Brazos County. It crosses U.S. Highway 190 (US 190) and SH 6 north of Bryan. Just west of this intersection, it begins to run along the county line between Brazos County and Robertson County. Upon crossing the Navasota River, OSR continues as the county line, this time between Leon County and Madison County. It passes through Normangee and crosses Interstate 45 (I-45). East of I-45, OSR crosses solely into Madison County and ends at Midway at another junction with SH 21.

History
SH OSR was originally designated on September 17, 1929, as Texas State Highway 938, to run from Midway to SH 6 (now also US 190) in Benchley, and a second section was designated from SH 21 northeast of Giddings to SH 29 (now US 183) north of Lockhart. On July 15, 1935, the section from SH 44 (now US 77) in Lincoln to SH 21 became part of SH 21. On April 19, 1938, the section from Lincoln to Bastrop also became part of SH 21. On March 26, 1942, a section from US 81 (now I-35) in San Marcos east 4.4 mi was added (creating a gap), and the designation was changed to SH OSR. On April 28, 1942, the road was extended from Benchley to SH 21 near the Brazos River. On August 2, 1943, the section from SH 29 to 4.4 mi east of San Marcos was added, closing the gap. Later that day, the section from Bastrop to San Marcos became part of SH 21.