List of suffixed Interstate Highways

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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
Formed: June 29, 1956[1]
Highway names
Interstates: Interstate X (I-X)
System links

Currently the Interstate Highway System includes seven suffixed routes that are signed: the Interstate 35 split into Interstate 35E and Interstate 35W at Dallas-Fort Worth, Texas; a similar split into Interstate 35E and Interstate 35W at Minneapolis-St. Paul, Minnesota; as well as Interstate 69C, Interstate 69E and Interstate 69W in South Texas; in addition, Interstate 480N in Ohio exists and is designated as such on mile markers but is otherwise unsigned. However, there were once many more, 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, AASHTO abolished the majority of suffixes due to confusion, renumbering them as three-digit Interstates, but several that return to their parents were kept. For example, Interstate 15E has since become Interstate 215, but both I-35E/I-35W and I-69 splits still exist.


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 1958 1982 Replaced by I-5
I-15E I-15 in Temecula, CA I-15 in Devore, CA 1973 1982 Renumbered from I-215 in 1973 and back to I-215 in 1982
I-15W I-15 in Pocatello, ID I-80N in Rupert, ID 1958 became I-86 in 1980; was also planned as I-82N
I‑24W I-40 in Jackson, TN I-55 in Hayti, MO 1964 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 1959 current
I-35E 96.76 155.72 I-35 in Hillsboro, TX I-35 in Denton, TX
I-35W I-35 in Wichita, KS I-70 in Salina, Kansas 1976[2] Renumbered I-135[2]
I-35W 41.78 67.24 I-35 in Burnsville, MN I-35 in Forest Lake, MN
I-35E 39.34 63.31 I-35 in Burnsville, MN I-35 in Forest Lake, MN
I‑59B 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 2014 current
I-69C 18.02 29.00 I-2/US 83/US 281 in Pharr, TX US 281/Bus. US 281 near Edinburg, TX 2013 current
I-69E 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
2011 current
I-70S I-70 in Washington, PA I-70/I-80S in New Stanton, PA 1958 1964 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 1958 1973
I-70S I-70 in Frederick, MD I-66/I-95 in Washington, DC 1958 1973
I-75E Bypass for I-75 around Tampa-St. Petersburg, FL 1973 Renumbered I-275; later swapped with I-75 in 1980
I‑80N I-80 in Echo, UT I-5 in Portland, OR 1958 1980 Became I-84
I‑80S I-25/I-70 in Denver, CO I-80 in Big Springs, NE 1958 1980 became I-76
I-80N I-80 in Neola, IA I-29 in Loveland, IA 1973 Became part of I-680
I-80N I-80/I-90 in Lorain County, OH I-80S/SR 5 in Braceville Township, OH 1960 1962 Redesignated as I-80
I‑80S I-80 in Youngstown, OH I-295 in Camden, NJ 1970 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 in Crescent Lake, PA 1964 Formerly I-82, became I-81E (now I-380)
I-81E I-81 in Scranton, PA I-80 in Scotrun, PA 1964 1973 Formerly I-81S, became I-380
I‑82S Burley, ID Tremonton, UT 1957 Became I-84
I-82N Burley, ID Pocatello, ID 1957 Became I-86
I-90N Buffalo, NY Canadian border at Lewiston, NY 1957 1959 Original designation for I-190 in New York, renamed I-190
I-94N Muskegon, MI I-94 in Grand Rapids, MI 1957 1959
I-180N I-80N Boise, ID 1980 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-480N 1.99[3] 3.20 I-480 in Maple Heights, OH US 422 in Warrensville Heights, OH 1974 current Signed as I-480 on guide signs and reassurance markers, signed as I-480N on mile markers
  •       Former


  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 March 16, 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 July 16, 2013. 
  3. ^ Office of Technical Services (January 1999). "Technical Services Straight Line Diagram for I-480N" (PDF). Ohio Department of Transportation. 

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