The highway is a limited access freeway from US 75 to SH 91.

The rest of the route is a surface street to its terminus at US 69.

The highway was originally part of US 75 until the "Katy Memorial Freeway" was built to bypass Denison.

On December 21, 1994, Spur 503 was extended from SH 91 to US 69, replacing part of Business U.S. 75.

The entire route is in Denison, Grayson County.