Interstate 45 (I-45[a]) is a major Interstate Highway located entirely within the U.S. state of Texas. While most primary Interstate routes which have numbers ending in "5" are cross-country north–south routes, I-45 is comparatively short, with the entire route located within Texas. Additionally, it has the shortest length of all the primary Interstates that have numbers ending in a "5". It connects the cities of Dallas and Houston, continuing southeast from Houston to Galveston over the Galveston Causeway to the Gulf of Mexico.
I-45 replaced U.S. Highway 75 (US 75) over its entire length, although portions of US 75 remained parallel to I-45 until its elimination south of Downtown Dallas in 1987. At the south end of I-45, State Highway 87 (SH 87, formerly part of US 75) continues into downtown Galveston. The north end is at I-30 in Downtown Dallas, where US 75 used the Good-Latimer Expressway. A short continuation, known by traffic reporters as the I-45 overhead,[3] signed as part of US 75, and officially I-345, continues north to the merge with the current end of US 75. Traffic can use Spur 366 (better known locally as the Woodall Rodgers Freeway) to connect to I-35E at the north end of I-345.
The portion of I-45 between Downtown and Galveston is known to Houston residents as the Gulf Freeway. The short elevated section of I-45, which forms the southern boundary of Downtown, is known as the Pierce Elevated after the surface street next to which the freeway runs, while north of I-10 it is known as the North Freeway. I-45 and I-345 in the Dallas area, north of the interchanges with I-20 and SH 310 (old US 75), is the Julius Schepps Freeway. The Gulf Freeway and North Freeway both include reversible high-occupancy vehicle lane (HOV lanes) for busses and other HOVs to and from Downtown.
The freeway is the subject of ongoing controversy and federal investigation due to a proposed expansion project in Harris County, which would displace hundreds of people from their homes and worsen air quality.[4] The local authorities have opposed the expansion project, while the Texas Department of Transportation (TxDOT) supports expansion, and negotiations are pending.[5][6] The project's estimated cost is at least $9.7 billion and is expected to take at least two decades to complete.[7][8]
In addition to the official control cities of Galveston, Houston, and Dallas,[9] I-45 serves a number of other communities, including La Marque, League City, Spring, The Woodlands, Conroe, Willis, Huntsville, Madisonville, Centerville, Buffalo, Fairfield, Corsicana, and Ennis.
US 190 joins I-45 for 26 miles (42 km) from Huntsville to Madisonville. US 287 joins I-45 for 18 miles (29 km) from Corsicana to Ennis. US 287 signs are only posted (with I-45) from the northern end of Business I-45-F (Bus. I-45-F) in Corsicana to the Ellis County line.
I-45 gained notoriety during Hurricane Rita in 2005. Thousands of Houston area evacuees jammed the roadway trying to leave. As a result, the freeway became a parking lot. Gas stations ran dry and hundreds of people's cars simply ran empty, their occupants having to spend the night along the shoulder. Four-hour drives suddenly became 24-hour drives. Even though TxDOT started contraflow lane reversal at Farm to Market Road 1488 (FM 1488), it did not alleviate the traffic jam deep into the city, as that starting point was even north of The Woodlands, which is close to Conroe, the northern terminus of Greater Houst