# List of suffixed Interstate Highways

In the United States, there are currently eight 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 four 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

| Number | Length (mi) | Length (km) | Southern or western terminus | Northern or eastern terminus | Formed | Removed | Notes |
| I-5W | — | — | I-5 in Tracy, CA | I-5 in Dunnigan, CA | — | — | Replaced by I-580, I-80 and I-505 |
| I-5E | — | — | I-5 in Tracy, CA | I-5 in Dunnigan, CA | 01958-01-011958 | 01982-01-011982 | Replaced by I-5 |
| I-15E | — | — | I-15 in Temecula, CA | I-15 in Devore, CA | 01973-01-011973 | 01982-01-011982 | Renumbered from I-215 in 1973 and back to I-215 in 1982 |
| I-15W | — | — | I-15 in Murrieta, CA | I-15 in San Bernardino, CA | 01957-01-011957 | — | Became I-15 in 1957 |
| I-15W | — | — | I-80N in Rupert, ID | I-15 in Pocatello, ID | 01958-01-011958 | 01980-01-011980 | Became I-86 in 1980; was also planned as I-82N |
| I-24W | — | — | I-55 in Hayti, MO | I-40 in Jackson, TN | — | 01964-01-011964 | Did not connect to I-24; renumbered I-155 |
| I-35W | 85.20 | 137.12 | I-35 in Hillsboro, TX | I-35 in Denton, TX | 01959-01-011959 | current | |
| I-35E | 96.76 | 155.72 | I-35 in Hillsboro, TX | I-35 in Denton, TX | 01959-01-011959 | current | |
| I-35W | — | — | I-35 in Wichita, KS | I-70 in Salina, Kansas | — | 01976-01-011976 | Renumbered I-135 |
| I-35W | 41.78 | 67.24 | I-35 in Burnsville, MN | I-35 in Forest Lake, MN | 01960-01-011960 | current | |
| I-35E | 39.34 | 63.31 | I-35 in Burnsville, MN | I-35 in Forest Lake, MN | 01970-01-011970 | current | Trucks over 9,000 lb (4,100 kg) gross weight prohibited between MN 5 and I-94 |
| I-59B | — | — | Bypass for I-59 around Birmingham, AL | Bypass for I-59 around Birmingham, AL | — | — | Renumbered I-459 |
| I-69W | 1.43 | 2.30 | Fed. 85D at Mexican border on World Trade International Bridge at Laredo, TX | I-35/US 83/US 59/Loop 20 in Laredo, TX | 02014-01-012014 | current | Partially completed |
| I-69C | 18.02 | 29.00 | I-2/US 83/US 281 in Pharr, TX | US 281/FM 490 in Edinburg, TX | 02013-01-012013 | current | Partially completed |
| I-69E | 81.00 | 130.36 | East Rio Grande Valley segment: US 77/US 83/University Boulevard in Brownsville, TXCorpus Christi area segment: US 77/FM 1356 in Kingsville, TX | East Rio Grande Valley segment: US 77 near Raymondville, TXCorpus Christi area segment: I-37/US 77 in Corpus Christi, TX | 02011-01-012011 | current | Partially completed |
| I-70S | — | — | I-70 in Washington, PA | I-70/I-80S in New Stanton, PA | 01958-01-011958 | 01964-01-011964 | Became part of I-70 and former I-70 became parts of I-79 and I-76 |
| I-70N | — | — | I-70 in Frederick, MD | I-83/I-95 in Baltimore, MD | 01958-01-011958 | 01973-01-011973 | Became I-70 |
| I-70S | — | — | I-70 in Frederick, MD | I-66/I-95 in Washington, DC | 01958-01-011958 | 01973-01-011973 | Became I-270 |
| I-75E | — | — | Bypass for I-75 around Tampa-St. Petersburg, FL | Bypass for I-75 around Tampa-St. Petersburg, FL | — | 01973-01-011973 | Renumbered I-275; later swapped with I-75 in 1973 |
| I-80N | — | — | I-5 in Portland, OR | I-80 in Echo, UT | 01958-01-011958 | 01980-01-011980 | Became I-84 |
| I-80S | — | — | I-25/I-70 in Denver, CO | I-80 in Big Springs, NE | 01958-01-011958 | 01980-01-011980 | Became I-76 |
| I-80N | — | — | I-80 in Neola, IA | I-29 in Loveland, IA | — | 01973-01-011973 | Became part of I-680, then I-880 after I-680 was split |
| I-80N | — | — | I-80/I-90 in Lorain County, OH | I-80S/SR 5 in Braceville Township, OH | 01960-01-011960 | 01962-01-011962 | Redesignated as I-80 |
| I-80S | — | — | I-80 in Youngstown, OH | I-295 in Camden, NJ | — | 01970-01-011970 | Extended west to Lodi, OH, by 1962 over former I-80; east end truncated to Monroeville, PA, and the part east of Monroeville renumbered I-76 in 1964; the rest became part of I-76 |
| I-81S | — | — | I-81 in Scranton, PA | I-80 at Crescent Lake | — | 01964-01-011964 | Formerly I-82, became I-81E (now I-380) |
| I-81E | — | — | I-81 in Scranton, PA | I-80 in Scotrun, PA | 01964-01-011964 | 01973-01-011973 | Formerly I-81S, became I-380 |
| I-82S | — | — | Burley, ID | Tremonton, UT | 01957-01-011957 | — | Became I-84 |
| I-82N | — | — | Burley, ID | Pocatello, ID | 01957-01-011957 | — | Became I-86 |
| I-90N | — | — | Buffalo, NY | Canadian border at Lewiston, NY | 01957-01-011957 | 01959-01-011959 | Original designation for I-190 in New York, renamed I-190 |
| I-94N | — | — | Muskegon, MI | I-94 in Grand Rapids, MI | 01957-01-011957 | 01959-01-011959 | Became I-196 in 1959 and then I-96 in 1964 |
| I-95E | — | — | East Providence, RI | - | 01957-01-011957 | 01959-01-011959 | Renumbered I-195 |
| I-180N | — | — | I-80N | Boise, ID | — | 01980-01-011980 | This was the only suffixed three-digit Interstate (until I-480N in Ohio was designated); all other spurs of suffixed routes had no suffix; became I-184 |
| I-270Y | 2.10 | 3.38 | I-270 in Bethesda, MD | I-495 in Bethesda, MD | 01975-01-011975 | current | Signed as I-270 Spur; designated internally by MDSHA as I-270Y. |
| I-480N | 1.99 | 3.20 | I-480 in Maple Heights, OH | US 422 in Warrensville Heights, OH | 01974-01-011974 | current | Signed as I-480 on guide signs and reassurance markers, signed as I-480N on mile markers |
| I-495X | 1.50 | 2.41 | I-495 in Bethesda, MD | Clara Barton Parkway in Cabin John, MD | 01965-01-011965 | current | Also known as Cabin John Parkway; designated internally by MDSHA as I-495X; unsigned; trucks are not allowed on the length of the freeway |
| I-895A | 0.71 | 1.14 | I-895B in Brooklyn Park, MD | I-97 in Ferndale, MD | 01965-01-011965 | current | Unsigned. Internally designated by MDSHA as I-895A |
| I-895B | 2.67 | 4.30 | I-895 in Brooklyn Park, MD | Governor Ritchie Highway in Glen Burnie, MD | 01965-01-011965 | current | Unsigned. Internally designated by MDSHA as I-895B |
| Former ||||||||