Spur 303 is a state highway between Interstate 820 in Fort Worth, and Duncanville Road in Dallas. At 17.4 miles in length, it is Texas' longest highway spur.
The portion in Dallas between Loop 12 and Mountain Creek Parkway (near Dallas Baptist University) is officially designated Kiest Boulevard, and it also passes over the Mountain Creek Lake Bridge (however, the stretch between Mountain Creek Parkway and SE 14th Street, which is the location of the bridge, is not part of the Spur)
. The portion in Arlington and Grand Prairie is designated Pioneer Parkway. The portion in Fort Worth is designated Rosedale Street and ends at Interstate 820.
Spur 303, known as "Kiest Boulevard" starts at an intersection in Dallas, with Walton Walker Boulevard (Loop 12), continuing onto Mountain Creek Parkway, and the Mountain Creek Bridge, and heading to Grand Prairie, at this point the road is named "Pioneer Parkway" after the Pioneer Trail. After a few miles of passing several shopping centers, and intersecting with the loop road known as Belt Line Road, Spur 303 has an interchange with SH 360 in Arlington city limits, after intersecting FM 157 (Cooper Street), and running parallel with SH 180 for a while, Spur 303 enters Fort Worth city limits. At this point, the road is known as "Rosedale Street". Spur 303 later terminates at an interchange with I-820
Spur 303 was designated on February 23, 1956, from Rosedale Street to SH 360. On May 23, 1956, it extended east to FM 1382. On March 7, 1969, Spur 303 extended east to Loop 12. On July 24, 1978, the section from 14th Street to Florina Drive and Kiest Boulevard was given to the city of Grand Prairie.