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I-181 (numbered as another interstate) Tennessee
Originally a freeway upgrade to US 23 in northeastern Tennessee, Interstate 181 survived nearly 20 years with the 181 designation, and is now part of the extended Interstate 26.
I-181 was created in late 1985, truncated when I-26 reached I-40 in 2003, and deleted when I-26 was extended further north in August 2005. At its creation, I-181 was 23.85 miles long .
Federal program funds US 23 upgrades, but withers
Interstate 181 is part of the Appalachian Corridor B, a route from the 1960s slated to run along US 23 from Columbus, Ohio to Asheville, North Carolina. In 1965 the Johnson Administration created the Appalachian Development Highway Program (ADHP) under the Appalachian Regional Commission (ARC) to widen highways throughout the region. US 23, one of these Appalachian Highways, was widened from Kingsport to Johnson City in the 1970s. 
The intent had always been to four-lane US 23 to both state lines. In 1980, the incoming administration slashed ARC funds, and many highways, including four-laning US 23 south to Asheville, languished. 
I-181 is born
In summer 1985, two city planners for Johnson City realized that the US 23 expressway met all standards for an interstate highway, and could be signed as one for about $100,000.
Eddie Williams, CEO of economic development for Johnson City, Jonesborough and Washington County, liked the idea and sent a memo to the Tennessee DOT commissioner on Aug. 28, 1985 requesting part of US 23 to be designated Interstate 181. The DOT and FHWA concurred, and on Dec. 27, 1985, Williams' office issued a press release titled "Johnson City now has an Interstate Highway." 
The new designation included 23.85 miles of US 23, between exit 55 in Kingsport and exit 31 in Johnson City. 
Without I-181, would there have been an I-26 extension?
Tennessee' designation of I-181, and its intent to extend the expressway to the NC state line, spurred North Carolina to talk about widening US 23 on its side. There were fears of safety problems as four lanes of expressway traffic were dumped onto a two-lane road, and hopes of economic expansion as the Johnson City area was better linked to Asheville.
You could say Tennessee leaned on NC a little when its 1986 TIP set widening US 23 to the NC state line as its top priority. 
North Carolina's 1989 Trust Fund deserves credit for I-26 as well. The $93 billion highway fund was devised to build 3,600 miles of four-lane highways, enough to place every state resident within ten miles of one. Former Asheville mayor Louis Bissette said that without the Trust Fund, I-26 would not have happened. 
I-26 extended, absorbs part of I-181
On Aug. 5, 2003, Interstate 26 was extended north from Asheville, N. C. to I-81, incorporating all of I-181 south of I-81.  This numbering was approved by AASHTO on June 8, 1988, "subject to FHWA concurrence and contingent upon the removal of the I-181 designation in Tennessee between Johnson City and I-81."  FHWA agreed to this in 1995 and again in 2003.
Contention surrounded future I-26 designation
It was entirely confusing to suggest that the exact same interstate capacity road that we have traveled for years would have been called I-26 on one side while remaining I-181 on the other.In 2003, as the completion date for I-26 approached, there was discussion over what to do with the portion of I-181 north of I-26. As far as AASHTO was concerned, that part would remain I-181. Tennesee DOT, however, was planning to call it Interstate 126. 
Tennessee Rep. Bill Jenkins, on 2005 effort to extend I-26 over I-181 
Officials in Kingsport, however, preferred that the I-26 designation extend to the Virginia state line, to give the city a 2-digit interstate. (These are considered preferable to 3-digit interstates for prestige and economic opportunities.) In order to bolster their case, they noted the existence of a state route 126 in the area could invite confusion with I-126.  In the case nothing other than an x26 spur would satisfy TDOT, a Kingsport neighborhood council president in June 2003 recommended I-326 or I-526, to avoid the conflict with state route 126. 
Kingsport lobbying continued until about a month before I-26 opened. As it stood immediately after the opening, I-181 is the number north of I-81; I-26 won't be extended past I-81; and I-126 may still be in play. 
There hasn't been much talk of I-126 throughout 2004, so that idea is probably moribund.
Kingsport? It's over on the coast, near Innsmouth
Kingsport officials are not satisfied with I-26 signs, which display mileage and directions to only two of the Tri-Cities: Bristol and Johnson City. Adding Kingsport would be nice, it is said, but extending I-26 would be even better: "Our main focus is to get I-26 to the Virginia state line," Jeff Fleming, Kingsport's assistant city manager for development, told the Times-News. "That's our number one priority." 
Extension of I-181 sought
In 1998, Virginia Congressman Rick Boucher was seeking to have US 23 upgraded in Virginia and added to I-181. 
... did I say I-181? I meant to say I-26
In August 2005, Tennessee Sens. Bill Frist and Lamar Alexander, and Rep. Bill Jenkins announced that the new Safe, Accountable, Flexible, and Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) highway bill conference report includes an extension of I-26 to not only absorb I-181, but extend to the Virginia state line.  The bill became law on Aug. 10, 2005.
I-281 (numbered as another interstate) New York
A portion of I-281, between Jamesville and NY 5, opened in the 1960s. The rest, including a planned northward extension back to I-81, was not yet open when the numbering change was announced. 
I-381 (preliminary numbering) New York
On Aug. 22, 1958, New York submitted the number I-381 for a proposed southeastern bypass of Syracuse. On Aug. 29, 1958, AASHO directed the state to change the number to I-281, since it connected two interstates (I-81 and today's I-690). 
In 1970, the road was renumbered again, to I-481.
I-481 New York
15.04 miles ; east loop of I-81 in Syracuse. The NY 481 freeway continues for 21 miles to the northwest, ending in Fulton.
Earlier numberings for the southern half of Interstate 481 were I-381 (proposed in 1958) and I-281 (the number accepted in 1958). I-281 became I-481 on Jan 1, 1970. 
A portion in the south, between Jamesville and NY 5, opened in the 1960s. The approach to I-90 was under construction in late 1969. 
The northern half was approved by the state in the early 1960s, but federal funding wasn't available (until 1968, probably). A link from I-90 to Northern Blvd. opened on Dec. 13, 1984.  It was completed to I-81 in fall 1986. 
Might I-481 get Wilmingtoned?
In 2001, a Syracuse city councilman proposed tearing down the I-81 viaduct in the downtown area and rerouting I-81 along I-481. If this is done, the I-481 designation would be eliminated, similar to what is planned for I-495 around Wilmington, Del. The remaining portions of I-81 leading into Syracuse could be assigned new spur numbers, such as 781 and 981. 
I-581 was built with six lanes, and opened in stages from Dec. 1964 to Oct. 1967. 
On July 25, 1996, AASHTO approved the designation of I-73 and I-74 in South Carolina, North Carolina, and Virginia; the I-73 path includes all of I-581.