State Highway 45 is a freeway loop around Austin, Texas, that exists in two open segments. The official designation of SH 45 is such to form a complete loop around Austin, a distance of roughly 80 miles (130 km).

Quick Facts State Highway 45, Route information ...

State Highway 45
Route information
Length	25.024 mi[1] (40.272 km)
Existed	1985–present
Major junctions
Beltway around Austin
Southwestern segment
CCW end	FM 1626 in Austin
Major intersections	Loop 1
CW end	RM 1826 in Austin
Eastern segment
CCW end	RM 620 in Austin
Major intersections	US 183 Loop 1 Toll I-35 SH 130 Toll US 290 SH 71 US 183 SH 130 Toll
CW end	I-35 in Austin
Location
Country	United States
State	Texas
Highway system
Highways in Texas Interstate US State Toll Loops Spurs FM/RM Park Rec
← I-45 → SH 46

Close

One segment is in southwest Austin and runs southeast from Ranch to Market Road 1826 to Farm to Market Road 1626 and intersects the southern terminus of Loop 1 (Mopac Expressway). Between RM 1826 and Loop 1, the roadway is a divided four-lane facility with a wide median intended to accommodate a future freeway, after which the current lanes would serve as frontage roads. Between Loop 1 and FM 1626, the roadway becomes a tolled freeway.

The other segment is a toll road that forms a backwards C-shape along the boundary of Travis and Williamson County before bending down along the eastern edge of the Austin metropolitan area where it shares its route with SH-130.

Before the 2002 Central Texas Turnpike Project (CTTP), SH 45 existed only as a short section of four-lane, divided highway in southwest Austin. The CTTP added a toll road that runs east from US 183 near Cedar Park, crosses I-35, bi-secting the La Frontera development, and meets SH 130 near Pflugerville. South of this interchange, SH 45 is co-signed with SH 130 to US 183 just south of Austin-Bergstrom International Airport. SH 45 then loops westward rejoining I-35 north of Buda.

State Highway 45 was originally designated on August 18, 1919, as a route from Bryan to the Louisiana border.^[9] On September 17, 1923, the section west of Roans Prairie was cancelled.^[10] On August 11, 1925, SH 45 was rerouted through Point Blank, Coldspring and Shepherd.^[11] On March 19, 1929, a branch of SH 45 on a more direct route from Point Blank to Livingston was designated.^[12] As of March 19, 1930, large portions of the highway were still under construction along the proposed route. The section of the branch from Point Blank to Coldspring was renumbered as SH 156 and the section of the branch from Coldspring to Shepherd was renumbered as part of SH 150, so that SH 45 went on the most direct route between Point Blank and Livingston. By 1938, the road was complete, with small portions remaining as a dirt road. On September 26, 1939, the highway from Huntsville to Jasper had been transferred to U.S. Highway 190, the stretch from Jasper to the Louisiana state line transferred to SH 63, and the section from Roans Prairie to Huntsville redirected north to Crockett. on August 24, 1960, the stretch from Huntsville to Crockett was transferred to SH 19. On December 15, 1960, the rest of SH 45 was canceled and transferred to SH 30 to avoid confusion with I-45. The current route was designated, but not constructed, on May 22, 1985, as a proposed Austin Loop, along with SH 130 (north of US 183 only).

SH 45A was a spur designated on September 14, 1926, from Coldspring west to New Waverly.^[13] On March 19, 1930, this spur was renumbered as SH 150.

On February 11, 2021, icy conditions caused a 26 vehicle pile-up. This incident occurred near the overpass with RM 620. Three people were hospitalized.^[14]

The interchange at I-35 was partially affected by the March 21, 2022 tornado outbreak when a large light pole was ripped off its foundation, the debris resting on the side of a flyover, as seen from photos captured by KXAN-TV.^[15]