Spur 3 begins at a junction with the SH 358 freeway. It travels north, first along Ennis Joslin Boulevard and then along Alameda Street. The route turns to the east at Ocean Drive. Signage indicating that state maintenance ends is present east of the Sand Dollar Boulevard entrance to TAMU-CC.
The original route with the Loop 3 designation was established on September 25, 1939, as a loop of US 81 in New Braunfels. A portion of that route became part of SH 46 during that route's extension on September 16, 1960, and the remainder was deleted from the state highway system on November 5, 1971. The current routing of Spur 3 was designated on February 23, 1993.