The I-635 (also known as the LBJ Freeway) is a "loop" freeway in Dallas-Ft. Worth, Texas. It circles the northeast perimeter of the Metroplex, beginning (or ending, depending how you look at it) State Highway 121 in Irving, just north of DFW Airport and ending at I-20 in southeast Dallas. I-635 is part of the Eisenhower Interstate System.

I-635 runs through the following Dallas-area cities: Irving, Coppell, Farmers Branch, Dallas, Garland, Mesquite and Balch Springs. It is a highway that is frequented by commuters, and traffic can quickly back up several miles during rush hour, especially if there is construction or an accident.

LBJ connects with the following major highways: Hwy 121, I-35 (Stemmons Freeway), the Dallas North Tollway, US 75 (Central Expressway), I-30 and I-20.