List of suffixed Interstate Highways
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Presently, the Interstate Highway System includes four suffixed routes - the Interstate 35 split into Interstate 35E and Interstate 35W at Dallas-Fort Worth, Texas and a similar split into Interstate 35E and Interstate 35W at Minneapolis-St. Paul, Minnesota. 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. Interstate 15E has since become Interstate 215, but both I-35E/I-35W splits still exist.
[edit] List of suffixed Interstates
| Number | Extent | Notes |
|---|---|---|
| Interstate 5W Interstate 5E |
Tracy, California (I-5) to Dunnigan, California (I-5) | In the 1958 plan; I-5E changed to I-5 and I-5W to I-580, I-80 and I-505 in 1964 |
| Interstate 15E | Temecula, California (I-15) to Devore, California (I-15) | Renumbered from I-215 in 1973 and back to I-215 in 1982 |
| Interstate 15W | Pocatello, Idaho (I-15) to Rupert, Idaho (I-80N) | In the 1958 plan; became I-86 |
| Interstate 24W | Jackson, Tennessee (I-40) to Hayti, Missouri (I-55) | Didn't connect to I-24; renumbered I-155 in 1964 |
| Interstate 35W Interstate 35E |
Hillsboro, Texas (I-35) to Denton, Texas (I-35) | In the 1958 plan; still exists |
| Interstate 35W | Wichita, Kansas (I-35) to Salina, Kansas (I-70) | In the 1958 plan; renumbered I-135 in 1980 |
| Interstate 35W Interstate 35E |
Lakeville, Minnesota (I-35) to Forest Lake, Minnesota (I-35) | Still exists |
| Interstate 59B | Bypass for I-59 around Birmingham, Alabama | Renumbered I-459 |
| Interstate 70S | Washington, Pennsylvania (I-70) to New Stanton, Pennsylvania (I-70/I-80S) | In the 1958 plan; became part of I-70 and former I-70 became parts of I-79 and I-76 in 1964 |
| Interstate 70S Interstate 70N |
Frederick, Maryland (I-70) to Washington, DC (I-66/I-95) and Baltimore, Maryland (I-83/I-95) | In the 1958 plan; became I-270 and I-70 in 1973 |
| Interstate 75E | Bypass for I-75 around Tampa-St. Petersburg, Florida | Renumbered I-275 in 1973, and swapped with I-75 in 1980 |
| Interstate 80N | Echo, Utah (I-80) to Portland, Oregon (I-5) | In the 1958 plan; became I-84 in 1980 |
| Interstate 180N | Spur from I-80N to Boise, Idaho | This was the only suffixed three-digit Interstate; all other spurs of suffixed routes had no suffix; became I-184 in 1980 |
| Interstate 80S | Big Springs, Nebraska (I-80) to Denver, Colorado (I-25/I-70) | In the 1958 plan; became I-76 |
| Interstate 80N | Neola, Iowa (I-80) to Loveland, Iowa (I-29) | Became part of I-680 in 1973 |
| Interstate 80N | Norwalk, Ohio (I-80/I-90) to Edinburg, Ohio (I-80) | In the 1958 plan; became part of I-80 by 1962 |
| Interstate 80S | Youngstown, Ohio (I-80) to Camden, New Jersey (I-295) | Extended west to Lodi, Ohio by 1962 over former I-80; east end truncated to Monroeville, Pennsylvania and the part east of Monroeville renumbered I-76 in 1964; the rest became part of I-76 in 1970 |
| Interstate 81E | Scranton, Pennsylvania (I-81) to Scotrun, Pennsylvania (I-80) | In the 1958 plan; became I-380 ca. 1973 |
[edit] References
| Main Interstate Highways (major in pink) |  |
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 4 | 5 | 8 | 10 | 12 | 15 | 16 | 17 | 19 | 20 | 22 | 24 | 25 | 26 | 27 | 29 |
| 30 | 35 | 37 | 39 | 40 | 43 | 44 | 45 | 49 | 55 | 57 | 59 | 64 | 65 | 66 | |
| 66 (W) | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 (W) | 76 (E) | 77 | 78 | |||
| 79 | 80 | 81 | 82 | 83 | 84 (W) | 84 (E) | 85 | 86 (W) | 86 (E) | 87 | |||||
| 88 (W) | 88 (E) | 89 | 90 | 91 | 93 | 94 | 95 | 96 | 97 | 99 | (238) | ||||
| H-1 | H-2 | H-3 | |||||||||||||
| Unsigned | A-1 | A-2 | A-3 | A-4 | PRI-1 | PRI-2 | PRI-3 | ||||||||
| Lists | Main - Auxiliary - Suffixed - Business - Proposed - Unsigned Gaps - Intrastate - Interstate standards - Replaced |
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