Texas State Highway 100
|Maintained by TxDOT|
|Length:||24.61 mi (39.61 km)|
|Existed:||1924 – present|
|West end:||I-69E / US 77 / US 83 / FM 1421 at Russeltown|
|East end:||PR 100 at the Queen Isabella Memorial Causeway at Port Isabel|
State Highway 100 or SH 100 is a Texas state highway that runs 24 miles (39 km) between "Russeltown" and Port Isabel. It was designated in 1926 along its current route. Its western terminus is at Interstate 69E/U.S. Highway 77/83 and ends at the western end of the Queen Isabella Memorial Causeway at Port Isabel. The route continues as Texas Park Road 100 east and north to a dead end on South Padre Island.
SH 100 was designated on September 15, 1924 on its current routing in Deep South Texas. Since its initial construction, the only change in the routing is in the city of Port Isabel, where the route was transferred to separate one way surface streets to better handle flow onto the Queen Isabella Causeway. On January 23, 1975, SH 100 extended east 0.5 miles over a section of PR 100.
SH 100 begins at an intersection with Interstate 69E/U.S. Route 77/U.S. Route 83 and Farm to Market Road 1421 at unincorporated Russelltown (formerly known as Barreda). The route travels due east, passing through downtown Los Fresnos. The route continues east before turning northeast where it formerly met Old Port Isabel Road, which connected Brownsville and Port Isabel. At this point the route becomes a 4-lane divided highway. The route continues northeast and east around the northern edge of Bahia Grande before reaching the southmost edge of Laguna Vista. The route then turns southeast, running along the coast of the Laguna Madre. Continuing southeast, it passes through the town of Laguna Heights, before reaching the city of Port Isabel. It reaches its eastern terminus at the Queen Isabella Causeway, which continues across the Laguna Madre to South Padre Island as Texas Park Road 100.
The entire route is in Cameron County.
|Brownsville||0.0||0.0||FM 1421 south (Rice Tract Road) / I-69E / US 77 / US 83||Western terminus; interchange; I-69E exit 14|
|3.5||5.6||FM 803 (Olmito North Road)|
|||5.1||8.2||FM 1575 (Old Alice Road)|
|Los Fresnos||6.5||10.5||FM 1847 (Arroyo Boulevard)|
|Laguna Vista||19.1||30.7||FM 510 (Santa Isabel Boulevard)|
|Port Isabel||23.1||37.2||SH 48 west (Brownsville-Port Isabel Highway) – Brownsville||Eastern terminus of SH 48|
|Laguna Madre||Queen Isabella Causeway|
|South Padre Island||24.6||39.6||PR 100 (Padre Boulevard) – Schlitterbahn Beach Waterpark||Eastern terminus|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi