State Highway OSR (SH OSR) is a 61.918-mile (99.647 km) non-numbered state highway in southeastern Texas, United States, that forms a northern loop off of Texas State Highway 21 (SH 21).
"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).
SH OSR was originally designated on September 17, 1929, as Texas State Highway 938,[2][3] 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 miles (7.1 km) 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 miles (7.1 km) east of San Marcos was added, closing the gap. Later that day, the section from Bastrop to San Marcos became part of SH 21.[1]
