In the United States, there are currently seven routes in the

Interstate Highway System The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. T ...

that are signed with letter suffixes to the route number.

Interstate 35 Interstate 35 (I-35) is a major Interstate Highway in the central United States. As with most primary Interstates that end in a five, it is a major cross-country, north–south route. It stretches from Laredo, Texas, near the Mexican border ...

(I-35) splits into

I-35E Interstate 35E may refer to: *Interstate 35E (Texas), a long branch route serving Dallas, Texas *Interstate 35E (Minnesota), a long branch route serving St. Paul, Minnesota See also * Interstate 35W (disambiguation) Interstate 35W may refer to: * ...

and

I-35W Interstate 35W may refer to: * Interstate 35W (Texas), an Interstate highway serving Fort Worth, Texas, and its suburbs * Interstate 35W (Minnesota), a Interstate highway serving Minneapolis, Minnesota, and its suburbs **The I-35W Mississippi Riv ...

in the Dallas–Fort Worth metroplex in Texas, and similarly splits into

and

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 Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

has several unsigned suffixed Interstate designations that are designated by the Maryland State Highway Administration, rather than by the

Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program ...

(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 The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United ...

(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

References

External links

* {{Interstates Suffixed Interstate Suffixed