|James H. Quillen Parkway|
|Maintained by TDOT|
|Length||57.5 mi  (92.5 km)|
|South end||I-26 / US 23 at the NC line|
|North end||US 23 at the VA line|
|Counties||Unicoi, Carter, Washington, Sullivan|
U.S. Route 23 (US 23) is a part of the U.S. Highway System that travels from Jacksonville, Florida to Mackinaw City, Michigan. In the U.S. state of Tennessee, the U.S. Highway travels 57.5 miles (92.5 km) from the North Carolina state line, at Sam's Gap, north to the Virginia state line, in Kingsport. With a predominant concurrency with Interstate 26 (I-26), US 23 is a divided four-lane freeway that follows Corridor B of the Appalachian Development Highway System and serves as a major thoroughfare in the Tri-Cities. The entire route of US 23 in Tennessee is an interstate-grade freeway.
US 23, in concurrency with I-26, enters Unicoi County at Sam's Gap (el. 3,799 ft (1,158 m)) and travels north along Stamp Ridge. Immediately after crossing the state line is a truck information station, signed "Truck Inspection," which requires all trucks to go through before continuing. The following 3 miles (4.8 km) is a 6% grade descent, accompanied with two runaway truck ramps, into the South Indian Creek valley. Between mile markers 47-48 is a scenic overlook turnoff (northbound US 23/westbound I-26 only), followed by the I-26 Erwin/Unicoi County Welcome Center, located on Clear Branch Road exit. At Temple Hill, US 19W, traveling from Burnsville, joins in concurrency.
After crossing the Nolichucky River, US 23 travels along the eastern foot of Buffalo Mountain as it goes through the towns of Erwin and Unicoi. Entering first in Carter County, US 23 enters Johnson City at the Okolona Road exit. Crossing soon afterwards into Washington County, US 23 connects with US 321/ SR 67, which goes to Elizabethton. At the Roan Street exit, US 19W splits off and joins US 11E, continuing towards Bluff City. Passing through Indian Ridge, US 23 leaves Johnson City proper, continuing northwesterly into Sullivan County.
After crossing the county and also entering Kingsport city limits, US 23 connects with I-81, in a cloverleaf interchange. At mile marker five is the I-26 Kingsport/Sullivan County Welcome Center, which is accessible from both directions. Staying west of downtown Kingsport, US 23 cuts through Bays Mountain and then crosses the south fork of the Holston River. At the US 11W (West Stone Drive) exit is the western terminus of I-26. With hidden concurrency with SR 137, US 23 continues north into Virginia, at Long Ridge, continuing towards Gate City.
|Location||NC state line– Kingsport, TN|
|Length||54.4 mi  (87.5 km)|
Interstate 26 (I-26) travels concurrently with US 23 from the North Carolina state line to US 11W (West Stone Drive) interchange in Kingsport. Established in August 2003, it replaced I-181 south of I-81 and displaced SR 36 and SR 81. In March, 2007, I-26 was extended north of I-81 to its current western terminus at US 11W, decommissioning I-181 completely, as all signs and exit numbers were changed-over to I-26's designation.
|Location||Kingsport, TN– VA state line|
|Length||3.0 mi   (4.8 km)|
State Route 137 (SR 137) is a hidden concurrency that overlaps US 23 between the US 11W (West Stone Drive) interchange and the Virginia state line, all within Kingsport.  Established in 1970 as a four-lane divided freeway, it traversed between SR 354, in Johnson City and SR 93, in Kingsport. SR 137 then expanded in phases: In 1973, extended south to US 11E/ US 19W; in 1976, extended south to SR 91; in 1978, extended south to US 321; by 1980, extended north to US 11W; and in 1985, extended north to the Virginia state line and south to Erwin. In December, 1985, I-181 was established, truncating SR 137 to its current routing today.
US 23 was established in 1930 with a complete concurrency with SR 36, from the North Carolina state line to the Virginia state line; going through Erwin, Unicoi, Johnson City and Kingsport.  In 1952, US 23 was rerouted southwest of Ernestville, along SR 81 through Flag Pond and Sam's Gap into North Carolina; its old alignment remained part of US 19W/SR 36.
In 1970, The first segment of a four-lane freeway, designated SR 137, was opened between Johnson City and Kingsport. Over the following decade, SR 137 continued being extended at both ends until in 1982, when AASHTO approved US 23 relocation onto the freeway, leaving behind its old alignment to SR 36 north of Johnson City to near the Virginia state line.  In December 1985, I-181 was established, truncated SR 137 north of US 11W, while SR 36 replaced as new concurrency south of US 11E; all signs and exit numbers were based on US 23 designation.  In 1988, AASHTO approved an extension of I-26 from North Carolina to I-81, on contingent upon the completion and certification of interstate standards in North Carolina, which happened in August 2003.  Following the new designation, both SR 36 and SR 81 was removed of their concurrencies with US 23. In March 2007, the remaining spur of I-181, from I-81 to US 11W, was switched to I-26.
|Location||Johnson City– Kingsport, TN|
|Length||23.85 mi  (38.38 km)|
Interstate 181 (I-181) was established in December 1985 as an interstate designation of US 23, which was already built to interstate standards in the 1970s. I-181 traversed from US 321/ SR 67, in Johnson City, to US 11W/ SR 1, in Kingsport, totaling 23.85 miles (38.38 km). US 23 continued on both directions as interstate grade to the Virginia line, to the north, and 15 miles (24 km) south to Erwin; by 1992, US 23 was upgraded to interstate grade south to Sam's Gap, at the North Carolina state line. All exit numbers were based on US 23 mileage. On August 5, 2003, after completion of a 9-mile (14 km) section completed in North Carolina, I-26 was extended west into Tennessee, replacing I-181 from Johnson City to I-81; north of I-81, I-181 continued into Kingsport. The American Association of State Highway and Transportation Officials (AASHTO) initially ruled against an extension of I-26 (as the number) along the remainder of I-181 to Kingsport, since that would give a main route Interstate Highway (I-26) a so-called "stub end," not connecting to any other Interstate highway, to an international border, or to a seacoast. The numerical extension was in 2005 enacted by the effect of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), signed into law on August 10, 2005. In March 2007, I-181 was officially decommissioned, as all signs and exit numbers were changed-over to I-26's designation.   
Old exit numbers were based on US 23 distances; new exit numbers are based on I-26 milemarkers.
|County||Location||mi  ||km||Old exit||New exit||Destinations||Notes|
|Unicoi||||54.4||87.5||I-26 east / US 23 south – Asheville||Continuation from North Carolina through Sam's Gap|
|||49.9||80.3||5||50||Flag Pond Road – Flag Pond|
|||46.3||74.5||9||46||Clear Branch Road – TN Welcome Center|
|Temple Hill||43.5||70.0||12||43||US 19W south (Temple Hill Road, SR 36) to SR 352||Southern end of US 19W concurrency|
|Erwin||39.8||64.1||15||40||Jackson-Love Highway – Erwin|
|37.2||59.9||18||37||SR 81 north / SR 107 – Erwin, Jonesborough, Greeneville||Southern terminus of SR 81|
|35.7||57.5||19||36||Harris Hollow Road to SR 107 (North Main Ave) – Erwin|
|Unicoi||33.7||54.2||21||34||Tinker Road – Unicoi|
|31.8||51.2||23||32||SR 173 east (Unicoi Road) – Unicoi|
|Carter||Johnson City||27.0||43.5||28||27||SR 359 north (Okolona Road) – Milligan College, Unicoi|
|Washington||23.8||38.3||31||24||US 321 / SR 67 – Elizabethton|
|23.0||37.0||32||23||SR 91 (Market Street, Main Street)|
|22.3||35.9||33||22||SR 400 (Unaka Avenue, Watauga Avenue)|
|20.2||32.5||35||20||US 11E / US 19W north (North Roan Street, SR 34)||Northern end of US 19W concurrency; signed as exits 20A (south) and 20B (north) westbound|
|19.0||30.6||36||19||SR 381 (North State of Franklin Road) – Bristol|
|16.7||26.9||38||17||SR 354 (Boones Creek Road) – Jonesborough|
|Gray||13.1||21.1||42||13||SR 75 (Suncrest Drive, Bobby Hicks Highway) – Gray|
|Sullivan||Kingsport||9.9||15.9||45||10||Eastern Star Road|
|8.5||13.7||46||8||I-81 – Knoxville, Bristol||Signed as exits 8A (south) and 8B (north)|
|6.3||10.1||49||6||SR 347 (Rock Springs Road)|
|4.0||6.4||51||4||SR 93 (John B. Dennis Highway) to SR 126 (Wilcox Drive)||Signed as exits 4A (south) and 4B (north) eastbound|
|0.0||0.0||55||1||I-26 end / US 11W (West Stone Drive, SR 1)||Western terminus of I-26; northern end of I-26 concurrency; southern terminus of SR 137; southern end of SR 137 concurrency|
|Virginia state line||57.3–|
|57||—||SR 36 south (Lynn Garden Drive) – Downtown Kingsport||Northbound left entrance extends into Virginia; left exit southbound|
|US 23 north – Gate City||Continuation into Virginia|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|
- Google (November 11, 2015). "U.S. Route 23 in Tennessee" (Map). Google Maps. Google. Retrieved November 11, 2015.
- Google (November 11, 2015). "Interstate 26 in Tennessee" (Map). Google Maps. Google. Retrieved November 11, 2015.
- Google (November 11, 2015). "Tennessee State Route 137" (Map). Google Maps. Google. Retrieved November 11, 2015.
- "General Highway Map, Sullivan County, Tennessee, 2005" (PDF). (4.85 MiB)
- Shell Highway Map of Kentucky Tennessee (PDF) (Map). Cartography Associates, David Rumsey Collection. 1956. Retrieved November 11, 2015.
- Special Committee on U.S. Route Numbering (June 28, 1982). "Route Numbering Committee Agenda" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 5. Retrieved November 11, 2015 – via Wikimedia Commons.
- Special Committee on U.S. Route Numbering (June 9, 1986). "Route Numbering Committee Agenda" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 2. Retrieved November 11, 2015 – via Wikimedia Commons.
- Special Committee on U.S. Route Numbering (June 7, 1988). "Route Numbering Committee Agenda" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 4. Retrieved November 11, 2015 – via Wikimedia Commons.
- Google (December 2, 2013). "Interstate 181 (Tennessee)" (Map). Google Maps. Google. Retrieved December 2, 2013.
- Allen, Calvin (July 16, 2003). "The Political History of I-26". Mountain Xpress. Asheville, NC. Retrieved December 2, 2013.
- Special Committee on U.S. Route Numbering (May 31, 2003). "Report of the Special Committee on U.S. Route Numbering to the Standing Committee on Highways" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 11. Archived (PDF) from the original on October 16, 2017. Retrieved December 2, 2013.
- Special Committee on U.S. Route Numbering (May 6, 2006). "Special Committee on U.S. Route Numbering Approved Applications" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. p. 1. Archived (PDF) from the original on October 16, 2017. Retrieved December 2, 2013.
- Media related to U.S. Route 23 at Wikimedia Commons
- Media related to Interstate 26 in Tennessee at Wikimedia Commons
- Media related to Tennessee State Route 137 at Wikimedia Commons
|U.S. Route 23|