Interstate 45 (I-45) is a major Interstate Highway located entirely within the U.S. state of Texas. While most Interstate routes which have numbers ending in "5" are cross-country north–south routes, I-45 is comparatively short, with the entire route located in Texas. Additionally, it has the shortest length of all the interstates that end 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.

Dallas is a city in the U.S. state of Texas and the most populous city in the Dallas–Fort Worth metroplex, the most populous metropolitan area in Texas and the fourth-most populous metropolitan area in the United States at 7.5 million people. It is the most populous city in and seat of Dallas County with portions extending into Collin, Denton, Kaufman, and Rockwall counties. With a 2020 census population of 1,304,379, it is the ninth-most populous city in the U.S. and the third-most populous city in Texas after Houston and San Antonio. Located in the North Texas region, the city of Dallas is the main core of the largest metropolitan area in the Southern United States and the largest inland metropolitan area in the U.S. that lacks any navigable link to the sea.