- Source: List of suffixed Interstate Highways
- List of suffixed Interstate Highways
- List of Interstate Highways
- State highways in New Jersey
- List of future Interstate Highways
- List of state routes in Arizona
- List of auxiliary Interstate Highways
- List of gaps in Interstate Highways
- Interstate 505
- Texas state highway system
- List of Interstate Highways in New York
In the United States, there are currently seven routes in the Interstate Highway System that are signed with letter suffixes to the route number. Interstate 35 (I-35) splits into I-35E and I-35W in the Dallas–Fort Worth metroplex in Texas, and similarly splits into I-35E and I-35W in the Minneapolis–St. Paul area in Minnesota. Other suffixed Interstates include I-69C, I-69E and I-69W in South Texas, and I-480N in Ohio, which is designated as such on mile markers but is otherwise unsigned. The state of Maryland has several unsigned suffixed Interstate designations that are designated by the Maryland State Highway Administration, rather than by the Federal Highway Administration (FHWA).
There were once many more suffixed Interstates, as the three-digit Interstates were not designated until after all major routes were assigned numbers. Most of these were spurs; the suffixed route did not return to its parent. In 1980, the American Association of State Highway and Transportation Officials (AASHTO) abolished the majority of suffixes due to confusion, renumbering them as three-digit Interstates. For example, I-15E in California has since become I-215.
List
See also
U.S. Roads portal
List of divided U.S. Routes
References
External links
Kirby, J.P.; et al. "Frequently Asked Questions - What are/where all the suffixed Interstates?". misc.transport.road.