List of Suffixed Interstate Highways
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List of Suffixed Interstate Highways

Dwight D. Eisenhower National System of Interstate and Defense Highways
Interstate 35E markerInterstate 69C marker
Highway shields for Interstate 35E and Interstate 69C
The 1958 Interstate Highway System plan included many suffixed Interstates.
System information
FormedJune 29, 1956[1]
Highway names
InterstatesInterstate X (I-X)
System links

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, including some short connections and spurs. (A few of the shortest, including I-190 and I-195, were assigned three-digit numbers almost immediately.) Most were not equal splits like on I-35, but had the main route continue through, and often the suffixed route never returned 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.


Number Length (mi) Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
-- -- I-5 in Tracy, CA I-5 in Dunnigan, CA -- -- Replaced by I-580, I-80 and I-505
-- -- I-5 in Tracy, CA I-5 in Dunnigan, CA 01958-01-011958 01982-01-011982 Replaced by I-5
-- -- 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-15 in Murrieta, CA I-15 in San Bernardino, CA 01957-01-011957 -- Became I-15 in 1957
-- -- 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-55 in Hayti, MO I-40 in Jackson, TN -- 01964-01-011964 Did not connect to I-24; renumbered I-155
85.20 137.12 I-35 in Hillsboro, TX I-35 in Denton, TX 01959-01-011959 current
96.76 155.72 I-35 in Hillsboro, TX I-35 in Denton, TX 01959-01-011959 current
-- -- I-35 in Wichita, KS I-70 in Salina, Kansas -- 01976-01-011976[2] Renumbered I-135[2]
41.78 67.24 I-35 in Burnsville, MN I-35 in Forest Lake, MN -- --
39.34 63.31 I-35 in Burnsville, MN I-35 in Forest Lake, MN -- --
-- -- Bypass for I-59 around Birmingham, AL -- -- Renumbered I-459
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
18.02 29.00 I-2/US 83/US 281 in Pharr, TX US 281/Bus. US 281 near Edinburg, TX 02013-01-012013 current
53.31 85.79 East Rio Grande Valley segment: US 77/US 83/University Boulevard in Brownsville, TX
Corpus Christi area segment: US 77/SH 44 in Robstown, TX
East Rio Grande Valley segment: US 77/Bus. US 77 near Raymondville, TX
Corpus Christi area segment: I-37/US 77 in Corpus Christi, TX
02011-01-012011 current
-- -- 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-70 in Frederick, MD I-83/I-95 in Baltimore, MD 01958-01-011958 01973-01-011973 Became I-70
-- -- I-70 in Frederick, MD I-66/I-95 in Washington, DC 01958-01-011958 01973-01-011973 Became I-270
-- -- Bypass for I-75 around Tampa-St. Petersburg, FL -- 01973-01-011973 Renumbered I-275; later swapped with I-75 in 1973
-- -- I-5 in Portland, OR I-80 in Echo, UT 01958-01-011958 01980-01-011980 Became I-84
-- -- I-25/I-70 in Denver, CO I-80 in Big Springs, NE 01958-01-011958 01980-01-011980 Became I-76
-- -- I-80 in Neola, IA I-29 in Loveland, IA -- 01973-01-011973 Became part of I-680
-- -- 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-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-81 in Scranton, PA I-80 at Crescent Lake -- 01964-01-011964 Formerly I-82, became I-81E (now I-380)
-- -- I-81 in Scranton, PA I-80 in Scotrun, PA 01964-01-011964 01973-01-011973 Formerly I-81S, became I-380
-- -- Burley, ID Tremonton, UT 01957-01-011957 -- Became I-84
-- -- Burley, ID Pocatello, ID 01957-01-011957 -- Became I-86
-- -- Buffalo, NY Canadian border at Lewiston, NY 01957-01-011957 01959-01-011959 Original designation for I-190 in New York, renamed I-190
-- -- Muskegon, MI I-94 in Grand Rapids, MI 01957-01-011957 01959-01-011959 Became I-196 in 1959[3] and then I-96 in 1964[4]
-- -- 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
2.10[5] 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.
1.99[6] 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
1.50[5] 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
0.71[5] 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
2.67[5] 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

See also


  1. ^ Weingroff, Richard F. (Summer 1996). "Federal-Aid Highway Act of 1956, Creating the Interstate System". Public Roads. Washington, DC: Federal Highway Administration. 60 (1). Retrieved 2012.
  2. ^ a b Kansas Department of Transportation (2009). "1970s". Kansas Celebrates 50 Years of Interstates. Kansas Department of Transportation. Archived from the original on February 12, 2012. Retrieved 2013.
  3. ^ "Spring to Bring Debut for Interstate Road Numbering". The Herald-Press. St. Joseph, Michigan. Associated Press. January 8, 1959. p. 5. OCLC 10117184. Retrieved 2018 – via
  4. ^ "Route Number Changes Slated". Lansing State Journal. December 12, 1963. p. 10. OCLC 61312043. Retrieved 2017 – via access
  5. ^ a b c d Highway Information Services Division (December 2013). "Highway Location Reference" (Webpage). Maryland Department of Transportation.
  6. ^ Office of Technical Services (January 1999). "Technical Services Straight Line Diagram for I-480N" (PDF). Ohio Department of Transportation.

External links

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