# U.S. Route 321

U.S. Route 321 (US 321) is a spur of U.S. Route 21. It runs for 516.9 miles (831.9 km) from Hardeeville, South Carolina to Lenoir City, Tennessee; with both serving as southern termini. It reaches its northernmost point at Elizabethton, Tennessee, just northeast of Johnson City. Because of its unusual "north–south–north" routing, U.S. Route 321 intersects both Interstate 40 and U.S. Route 70 three separate times. The highway serves different roles in each state: An alternate route to interstates in South Carolina, a major highway in North Carolina, and a scenic route in Tennessee.

## Route description

Lengths :
| | mi | km |
| SC | 217.2 | 349.5 |
| NC | 105.5 | 169.8 |
| TN | 194.2 | 312.5 |
| Total | 516.9 | 831.8 |

### South Carolina

US 321 provides direct access between Savannah and Columbia, serving as an alternate to Interstate 95 and Interstate 26. Starting in Hardeeville, US 321 as a mostly 2 lane highway goes through sparsely populated areas and small towns including Estill, Fairfax, and Denmark, heading in a rather straight and northward direction into the Columbia area, widening to a 5 lane highway right after Neeses, then narrowing down to a 2 lane highway right after the town of North and widening to a 5 lane highway again after Swansea and staying that way until it merges with its parent route US 21 in Dixiana. In Columbia, the route stays concurrent with US 21 through Cayce, over the Congaree River on the Blossom Street Bridge, turning left onto Huger Street, right onto Elmwood Avenue, and left onto North Main Street. The roads separate at Hyatt Park, with US 321 staying west of I-77 and US 21 north of Columbia. The route goes through to communities of Winnsboro, Chester, York, and Clover before entering North Carolina at Bowling Green.

### North Carolina

US 321 is an important route in Western North Carolina. It provides an alternative north–south route to I-77, which passes through a busy metropolitan area, and US 221, which is more twisty drive up the Appalachians. Travelers from South Carolina who are going to points west of Charlotte and want to avoid the traffic of I-77 may choose to enter the state on US 321.
The highway traverses through seven counties: Gaston, Lincoln, Catawba, Burke, Caldwell, Watauga, and Avery. US 321 has six control cities: Gastonia, Lincolnton, Hickory, Lenoir, Blowing Rock, and Boone.
US 321 is a multilane highway beginning at the state line. After 7 miles (11 km), it enters the Gastonia area. Traffic on northbound 321 through Gastonia is generally not as heavy as traffic on southbound 321 north of I-85, where it may back up for a couple of miles as drivers wait to turn onto I-85. The state completed a new interchange with I-85 in 2021 which has southbound 321 cross over 321NB at a stoplight just north of I-85. The traffic now enters I-85 northbound with a flyunder entrance ramp over a former railroad right-of-way.
The road becomes a freeway at C. Grier Beam Boulevard in Gastonia, just south of NC 275/NC 279. It remains a freeway until just north of its junction with US 70 in Hickory. The freeway bypasses a number of cities that the old US 321 route once passed through. Today, US 321 Business follows the original 38-mile (61 km) route, which serves Maiden, Newton, and Conover, but the freeway is a more direct route to the mountains, and the business route is generally used by local traffic only.
Traffic is usually heavy between Hickory and Lenoir. The North Carolina Department of Transportation (NCDOT) has a long-term plan to widen the road to six lanes, which is expected to begin after 2020.
North of Lenoir, US 321 is a four-lane divided highway, continuing up the steep escarpment of the Blue Ridge Mountains. Until early 2018, the road was a narrow two-lane highway from near Patterson through Blowing Rock. Work on this area continued for much of the first two decades of the 21st century. The widening of US 321 through Blowing Rock was and continues to be seen as a controversial project. Many residents of the town felt that a four-lane highway would destroy the character of the small town, and they proposed several bypass alternatives. NCDOT selected the widening as its preferred alternative, but added several features such as underground utilities, sidewalks, landscaping, and rock walls to make the widening more palatable to the residents opposed to it. These features were not present on the two-lane highway that was replaced. The final portion of the widening project, at the steepest part of the road just south of Blowing Rock, began in 2012 and was completed in 2018. Some landscaping work remains which will commence in Fall 2018 as its own project, constructed separately for beautification of the route through town.
North of Blowing Rock, US 321 is already a highway of four lanes up to King Street in Boone; thus, US 321 is a four-lane highway from the South Carolina state line to downtown Boone. Currently, US 321 meets US 421 at King Street and overlaps it over King Street to leave town to the west. NCDOT project R-2615 is proposed to widen the US 321/421 concurrency from this junction to their junction near Vilas, although this project is currently unfunded. There is a feasibility study (FS-0511A) in progress to examine the possibility of widening US 321 from the junction near Vilas to the Tennessee state line. If both of these projects were completed, then US 321 would be a four-lane highway through the entire state.

### Tennessee

As it crosses into Tennessee, US 321 enters the Cherokee National Forest, and continues westward through the rugged valley between Pond Mountain on the south and Watauga Lake on the north. The highway passes numerous campgrounds, boat launches, and other lake-related recreational areas as it winds its way along the shores of the lake. South of Butler, the highway joins SR 67, which enters from the Mountain City area to the northeast. The Appalachian Trail crosses US 321 at its intersection with Shook Gap Road, just before the highway exits the national forest. At Hampton, US 321 intersects US 19E, and the two highways run concurrently northward into Elizabethton.
US 321 inverts directions in Elizabethton: the road is designated as southbound in both directions driving away from its intersection with US 19E. It is conterminous with US 11E through portions of Washington and Greene counties. In Greeneville, the highway continues south into Cocke County. At the Cocke-Greene County line US 321 becomes a four-laned divided highway and bypasses Parrottsville. The four-lane section ends just before US 321's junction with SR 160 and crossing I-40 at Newport.
The stretch of US 321 from Newport south to Cosby and southwest through Pittman Center to Gatlinburg parallels the northern boundary of the Great Smoky Mountains National Park and is quite scenic. From a point between Newport and Cosby to the intersection with the Little River Road, it is concurrent with SR 73. In Pigeon Forge, concurrent with US 441/Great Smoky Mountains Parkway, US 321 is a divided, multi-lane traffic-laden thoroughfare where it serves as the city's main route, lined with hotels, outlet malls and amusement facilities. Veering southwest of Pigeon Forge, the highway takes on a more rural character as it traverses Wears Valley, and narrows down to two lanes until its junction with SR 73 Scenic (the Little River Road) at the Townsend entrance to the park. It is concurrent with SR 73 from this junction to its terminus. With the exception of a 3-mile (4.8 km) section between Townsend and Maryville, the remaining portions of the highway through Blount County are a minimum of four lanes and usually a divided highway. Once the highway reaches Fort Loudon Dam in Loudon County, it crosses the Tennessee River via a bridge, completed in 2017, southeast of the dam then intersects with US 11 in Lenoir City. US 321 has a wrong-way concurrency with SR 95 from a point several miles south of Lenoir City (near Greenback) to its terminus at I-40. In the northern part of Lenoir City, US 321 intersects I-75 and US 70 before reaching I-40. Beyond I-40, the road continues northward to Oak Ridge as the two-lane SR 95.
US 321 is a four-lane semi-divided thoroughfare from I-40 and I-75 to the Great Smoky Mountains National Park, except for the 3-mile (4.8 km) stretch near Walland.

## History
### North Carolina Highway 17

North Carolina Highway 17 (NC 17) was an original state highway that traversed from Hickory to Boone, through Granite Falls, Hudson, Lenoir and Blowing Rock. In 1930, it was extended south on new primary routing to NC 113, in Propst Crossroads; also same year, US 321 was established in the state and overlapped NC 17 between Hickory and Boone. In 1934, NC 17 was decommissioned, with US 321 taking all north of Hickory and NC 96 taking all south.

### North Carolina Highway 155

North Carolina Highway 155 (NC 155) was established in 1994 following the old alignment of US 321 as it was moved onto new four-lane controlled-access highway. From NC 275/NC 279, in Dallas, it traversed north through High Shoals to Lincolnton. Sharing a short concurrency with NC 150 as it bypass the downtown area of Lincolnton, it continues north meeting with main US 321, south of Maiden, continuing in concurrency through Newton and finally Conover, where it ended at US 70. In 1999, the remainder of US 321 was moved onto new freeway bypass west of Newton and Conover; at same time, NC 155 was decommissioned and absorbed into US 321 Business.

### North Carolina Highway 603
## Future

In addition to the widening project, there have also been talks of a freeway-to-freeway connection with Interstate 85 in Gastonia that would greatly relieve traffic flowing through the junction. Currently, US 321 is a surface road at the I-85 interchange, and is a limited access freeway a few hundred yards north. To extend the freeway to I-85, the remaining at-grade intersections and traffic lights would have to be eliminated.

## Major intersections

| State | County | Location | mi | km | Destinations | Notes |
| South Carolina | Jasper | Hardeeville | 0.0 | 0.0 | US 17 (Whyte Hardee Boulevard) – Ridgeland, Savannah | |
| South Carolina | Jasper | Hardeeville | 0.5 | 0.80 | SC 46 east (Church Road) | To Millstone Landing |
| South Carolina | Jasper | Tillman | 12.5 | 20.1 | SC 336 east (Tillman Road) – Ridgeland | |
| South Carolina | Jasper | Tarboro | 19.8 | 31.9 | US 601 north (Cypress Branch Road) – Hampton | Southern terminus of US 601 |
| South Carolina | Jasper | Robertville | 22.6 | 36.4 | SC 462 (Gillson Branch Road) – Pineland | |
| South Carolina | Hampton | Garnett | 25.6 | 41.2 | SC 119 south (Clyo Road) – Clyo, Springfield | |
| South Carolina | Hampton | Scotia | 30.7 | 49.4 | SC 333 (Scotia-Furman Highway) – Furman | |
| South Carolina | Hampton | Estill | 35.8 | 57.6 | SC 3 south (Third Street) – Lena | South end of SC 3 overlap |
| South Carolina | Hampton | Estill | 36.0 | 57.9 | SC 3 north (Nixville Road) – Barnwell | North end of SC 3 overlap |
| South Carolina | Hampton | ​ | 40.4 | 65.0 | SC 363 east (Luray Highway) – Hampton | To Lake Warren State Park |
| South Carolina | Allendale | Fairfax | 49.9 | 80.3 | US 278 (Allendale-Hampton Highway) – Allendale, Hampton | |
| South Carolina | Allendale | Sycamore | 55.6 | 89.5 | SC 641 (Confederate Highway) – Allendale | |
| South Carolina | Allendale | Ulmer | 59.9 | 96.4 | US 301 south (Burton's Ferry Highway) – Allendale | South end of US 301 overlap |
| South Carolina | Bamberg | ​ | 61.9 | 99.6 | US 301 north (Main Highway) – Bamberg | North end of US 301 overlap |
| South Carolina | Bamberg | Olar | 66.5 | 107.0 | SC 64 (Low Country Road) – Barnwell | |
| South Carolina | Bamberg | Denmark | 76.6 | 123.3 | SC 70 south (Hagood Street) – Barnwell | South end of SC 70 overlap |
| South Carolina | Bamberg | ​ | 76.9 | 123.8 | US 78 (Heritage Highway) – Bamberg, Blackville | |
| South Carolina | Bamberg | ​ | 77.3 | 124.4 | SC 70 north (Country Club Road) – Orangeburg | North end of SC 70 overlap |
| South Carolina | Orangeburg | Norway | 85.3 | 137.3 | SC 332 east (Cope Road) – Cope | East end of SC 332 overlap |
| South Carolina | Orangeburg | Norway | 85.6 | 137.8 | SC 332 west / SC 400 east (Norway Road) – Springfield, Orangeburg | West end of SC 332 overlap |
| South Carolina | Orangeburg | Neeses | 90.9 | 146.3 | SC 4 (Neeses Highway) – Springfield, Orangeburg | |
| South Carolina | Orangeburg | Neeses | 91.4 | 147.1 | SC 389 west (Ninety Six Road) – Perry, Wagener | |
| South Carolina | Orangeburg | North | 97.3 | 156.6 | US 178 (North Highway) – Pelion, Orangeburg | |
| South Carolina | Lexington | Swansea | 105.1 | 169.1 | SC 3 south (Whetstone Road) – Springfield, Blackville, Barnwell | |
| South Carolina | Lexington | Swansea | 105.9 | 170.4 | SC 692 south (Fifth Street) – Orangeburg | To Swansea High Football Stadium |
| South Carolina | Lexington | Swansea | 106.1 | 170.8 | SC 6 west (Second Street) – Lexington | West end of SC 6 overlap |
| South Carolina | Lexington | Swansea | 106.2 | 170.9 | SC 6 east (First Street) – St. Matthews | East end of SC 6 overlap |
| South Carolina | Lexington | ​ | 117.7 | 189.4 | US 21 south / US 176 east (Charleston Highway) – Orangeburg | South end of US 21 and east end of US 176 overlap |
| South Carolina | Lexington | Cayce | 120.2 | 193.4 | To I-77 north / Fish Hatchery Road – Charlotte | |
| South Carolina | Lexington | Cayce | 120.6 | 194.1 | I-26 – Charleston, Spartanburg | |
| South Carolina | Lexington | Cayce | 121.8 | 196.0 | SC 2 north (Frink Road) | |
| South Carolina | Lexington | West Columbia | 123.3 | 198.4 | SC 302 south (Airport Boulevard) – Aiken, Columbia Metropolitan Airport | |
| South Carolina | Lexington | West Columbia | 125.0 | 201.2 | SC 2 (State Street) | |
| South Carolina | Richland | Columbia | | | SC 48 Truck east (Blossom Street east / US 21 Conn. east / US 76 Conn. east) | Western terminus of US 21 Conn., the western segment of US 76 Conn., SC 48 Truck, and Blossom Street; US 21, US 176, and US 321 turn left off of Blossom Street onto Huger Street. |
| South Carolina | Richland | Columbia | 126.5 | 203.6 | US 1 / US 378 (Gervais Street) | To South Carolina State House |
| South Carolina | Richland | Columbia | 126.8 | 204.1 | SC 12 (Hampton/Tylor Streets) | To Finlay Park and Columbia Museum of Art |
| South Carolina | Richland | Columbia | 127.4 | 205.0 | I-126 west / US 76 west – Greenville, Spartanburg | West end of US 76 overlap |
| South Carolina | Richland | Columbia | 128.0 | 206.0 | US 76 east (Elmwood Avenue) | East end of US 76 overlap |
| South Carolina | Richland | Columbia | 128.6 | 207.0 | US 176 west (River Drive) | West end of US 176 overlap |
| South Carolina | Richland | Columbia | 129.2 | 207.9 | SC 16 (Sunset Drive) | |
| South Carolina | Richland | Columbia | 129.8 | 208.9 | SC 215 north (Montichello Road) | To Columbia International University |
| South Carolina | Richland | Columbia | 130.8 | 210.5 | US 21 north (Main Street) | North end of US 21 overlap; Columbia College at intersection |
| South Carolina | Richland | Columbia | 132.2 | 212.8 | I-20 – Florence, Augusta | |
| South Carolina | Fairfield | ​ | 151.2 | 243.3 | SC 269 south (Hinnants Store Road) | |
| South Carolina | Fairfield | Winnsboro Mills | 152.4 | 245.3 | SC 34 east – Ridgeway | East end of SC 34 overlap; to South Carolina Railroad Museum |
| South Carolina | Fairfield | Winnsboro Mills | 152.7 | 245.7 | US 321 Bus. north (Columbia Road) / SC 213 west (Monjicono Road) – Monticello | |
| South Carolina | Fairfield | Winnsboro | 156.1 | 251.2 | SC 34 west (Newberry Road) / SC 200 east – Newberry, Great Falls | West end of SC 34 overlap |
| South Carolina | Fairfield | Winnsboro | 156.9 | 252.5 | US 321 Bus. south (Congress Street) | |
| South Carolina | Chester | Chester | 178.8 | 287.8 | SC 97 south (Great Falls Road) – Great Falls, Camden | South end of SC 97 overlap |
| South Carolina | Chester | Chester | 179.4 | 288.7 | US 321 Bus. north (Columbia Road) SC 9 south / SC 72 east / SC 97 north / SC 121 north (J.A. Cochran Bypass) | South end of SC 9, east end of SC 72, and north end of SC 97/SC 121 overlap |
| South Carolina | Chester | Chester | 181.2 | 291.6 | SC 72 west / SC 121 south (West End Road) – Carlisle, Whitmire | West end of SC 72 and south end of SC 121 overlap |
| South Carolina | Chester | Chester | 182.0 | 292.9 | SC 9 Bus. south (Pinckney Street) | |
| South Carolina | Chester | Chester | 182.3 | 293.4 | SC 9 north (Pinckney Street) – Lockhart | North end of SC 9 overlap |
| South Carolina | Chester | Chester | 184.2 | 296.4 | US 321 Bus. south / SC 97 (Center Road) – Hickory Grove | |
| South Carolina | Chester | Lowrys | 189.7 | 305.3 | SC 909 south (Old York Road) – Lewis | |
| South Carolina | York | McConnells | 194.2 | 312.5 | SC 322 west (Church Street) | West end of SC 322 overlap |
| South Carolina | York | McConnells | 194.3 | 312.7 | SC 322 east (McConnells Highway) – Rock Hill | West end of SC 322 overlap; to Historic Brattonsville |
| South Carolina | York | York | 203.3 | 327.2 | US 321 Bus. (Congress Street) | |
| South Carolina | York | York | 203.7 | 327.8 | SC 49 (Sharon Road) – Sharon, Union | |
| South Carolina | York | York | 204.5 | 329.1 | SC 5 Bus. / SC 161 Bus. south (Liberty Street) – Blacksburg | South end of SC 161 Bus overlap |
| South Carolina | York | York | 205.7 | 331.0 | US 321 Bus. (Kings Mountain Street) | |
| South Carolina | York | York | 205.9 | 331.4 | SC 5 / SC 161 south (Alexander Love Highway) – Blacksburg | South end of SC 161 and north end of SC 161 Bus overlap |
| South Carolina | York | Filbert | 207.5 | 333.9 | SC 161 north – Bethany | North end of SC 161 overlap |
| South Carolina | York | Clover | 213.4 | 343.4 | SC 55 (Kings Mountain/Bethel Streets) – Lake Wylie, Blacksburg | |
| | | | 217.20.0 | 349.50.0 | South Carolina–North Carolina state line | South Carolina–North Carolina state line |
| North Carolina | Gaston | Gastonia | 7.3 | 11.7 | Garrison Boulevard | |
| North Carolina | Gaston | Gastonia | 7.9 | 12.7 | US 29 / US 74 (Franklin Boulevard) | |
| North Carolina | Gaston | Gastonia | 8.1 | 13.0 | NC 7 east (Long Avenue) | |
| North Carolina | Gaston | Gastonia | 9.4 | 15.1 | I-85 – Charlotte, Spartanburg | |
| North Carolina | Gaston | Dallas | 9.4 | 15.1 | Grier Beem Boulevard – Gaston College | Signed exit 11 |
| North Carolina | Gaston | Dallas | 11.7 | 18.8 | US 321 Bus. north / NC 275 / NC 279 (Dallas-Cherryville Highway) – Cherryville | Signed exits 12A-B Northbound and exit 12 Southbound |
| North Carolina | Gaston | ​ | 16.1 | 25.9 | Hardin Road | Signed exit 17 |
| North Carolina | Lincoln | ​ | 18.8 | 30.3 | US 321 Bus. (Gastonia Highway) – High Shoals, Lincolnton | Signed exit 20 |
| North Carolina | Lincoln | Lincolnton | 23.6 | 38.0 | NC 27 / NC 150 (Main Street) – Lincolnton | Signed exit 24 |
| North Carolina | Lincoln | ​ | 27.0 | 43.5 | US 321 Bus. (Maiden Highway) – Maiden | Signed exit 28 |
| North Carolina | Catawba | Maiden | 32.3 | 52.0 | Startown Road | Signed exit 33 |
| North Carolina | Catawba | ​ | 36.2 | 58.3 | NC 10 – Newton | Signed exit 37 |
| North Carolina | Catawba | ​ | 40.1 | 64.5 | River Road | Signed exit 41 |
| North Carolina | Catawba | Mountain View | 41.4 | 66.6 | NC 127 (Brookford Boulevard) | Signed exit 42 |
| North Carolina | Catawba | Hickory | 42.3 | 68.1 | I-40 – Statesville, Asheville | Signed exits 43A (east) and 43B (west) |
| North Carolina | Catawba | Hickory | 43.3 | 69.7 | US 70 / US 321 Bus. south to NC 127 (Conover Boulevard) – Hickory | Signed exit 44 |
| North Carolina | Catawba | Hickory | 45.3 | 72.9 | Clement Boulevard – Hickory Regional Airport | |
| North Carolina | Burke | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions |
| North Carolina | Caldwell | Northlakes | 47.9 | 77.1 | US 321A north – Granite Falls | |
| North Carolina | Caldwell | Granite Falls | 50.1 | 80.6 | Falls Avenue – Granite Falls | |
| North Carolina | Caldwell | Lenoir | 56.8 | 91.4 | Southwest Boulevard – Morganton | |
| North Carolina | Caldwell | Lenoir | 59.1 | 95.1 | US 321A south – Hudson | |
| North Carolina | Caldwell | Lenoir | 60.1 | 96.7 | US 64 / NC 18 / NC 90 east – Lenoir, Wilkesboro | East end of NC 90 overlap |
| North Carolina | Caldwell | Lenoir | 62.3 | 100.3 | NC 90 west (Main Street) – Lenoir, Collettsville | West end of NC 90 overlap |
| North Carolina | Caldwell | ​ | 65.9 | 106.1 | NC 268 east – Fort Defiance | |
| North Carolina | Watauga | Blowing Rock | 79.4 | 127.8 | US 321 Bus. north (Main Street) | |
| North Carolina | Watauga | Blowing Rock | 80.6 | 129.7 | US 221 south / US 321 Bus. south | South end of US 221 overlap |
| North Carolina | Watauga | Blowing Rock | 81.4 | 131.0 | Blue Ridge Parkway | To Moses H. Cone Memorial Park and Julian Price Memorial Park |
| North Carolina | Watauga | Boone | 87.0 | 140.0 | US 221 north / NC 105 – Linville, Banner Elk, Newland | North end of US 221 overlap |
| North Carolina | Watauga | Boone | 87.9 | 141.5 | US 421 south / NC 194 north (King Street) | South end of US 421 and north end of NC 194 overlap |
| North Carolina | Watauga | Vilas | 93.6 | 150.6 | NC 194 south – Valle Crucis | South end of NC 194 overlap |
| North Carolina | Watauga | Sugar Grove | 94.3 | 151.8 | US 421 north – Mountain City | North end of US 421 overlap |
| North Carolina | Avery | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions | No major junctions |
| | | | 105.50.0 | 169.80.0 | North Carolina–Tennessee state line | North Carolina–Tennessee state line |
| Tennessee | Carter | ​ | 12.5 | 20.1 | SR 67 east – Mountain City | East end of SR 67 and west end of SR 159 (hidden) overlap |
| Tennessee | Carter | Hampton | 12.5 | 20.1 | US 19E south (SR 37) – Roan Mountain | South end of US 19E overlap |
| Tennessee | Carter | Elizabethton | 27.2 | 43.8 | US 19E / SR 91 (SR 37) – Bluff City | North end of US 19E and SR 91 overlap |
| Route transition from northbound to southbound ||
| Tennessee | Carter | Elizabethton | 28.0 | 45.1 | SR 400 south – Watauga | |
| Tennessee | Carter | Elizabethton | 31.3 | 50.4 | SR 91 / SR 362 south | South end of SR 91 overlap |
| Tennessee | Carter | Elizabethton | 31.9 | 51.3 | SR 359 south – Milligan College | |
| Tennessee | Washington | Johnson City | 35.3 | 56.8 | Legion Street / Milligan Highway | Interchange |
| Tennessee | Washington | Johnson City | 35.8 | 57.6 | I-26 / US 19W / US 23 – Erwin, Kingsport | Intrechange; exit 24 (I-26) |
| Tennessee | Washington | Johnson City | 36.7 | 59.1 | SR 67 west / SR 381 (Cherokee Road) | West end of SR 67 and south end of SR 381 overlap |
| Tennessee | Washington | Johnson City | 39.5 | 63.6 | US 11E / SR 381 north (SR 34 / State of Franklin Road) | North end of US 11E and SR 381 overlap |
| Tennessee | Washington | Jonesborough | 44.3 | 71.3 | SR 354 (Boones Creek Road) / Boone Street – Boones Creek, Business District | |
| Tennessee | Washington | Jonesborough | | | To SR 81 / Washington Drive – Kingsport, Erwin, Business District | |
| Tennessee | Washington | Jonesborough | | | To SR 81 / Persimmon Ridge Road – Lamar, Erwin | |
| Tennessee | Washington | Limestone | 54.4 | 87.5 | SR 75 north (Opie Arnold Road) | |
| Tennessee | Greene | ​ | 58.0 | 93.3 | SR 351 (Chuckey Pike) – Chuckey, Rheatown | |
| Tennessee | Greene | Tusculum | 62.6 | 100.7 | SR 107 east (Tusculum Bypass) – Erwin, Tusculum College | East end of SR 107 (hidden) overlap |
| Tennessee | Greene | Greeneville | | | Erwin Highway – Tusculum, Tusculum College | Former SR 107 |
| Tennessee | Greene | Greeneville | 65.2 | 104.9 | US 11E Bus. south (SR 107 / Tusculum Boulevard) | West end of SR 107 (hidden) overlap |
| Tennessee | Greene | Greeneville | 66.0 | 106.2 | Snapps Ferry Road | Interchange |
| Tennessee | Greene | Greeneville | 67.1 | 108.0 | US 11E south (SR 34) / SR 93 north (Kingsport Highway) – Kingsport, Morristown | South end of US 11E overlap; southern terminus of SR 93 |
| Tennessee | Greene | Greeneville | 67.3 | 108.3 | SR 172 north (Baileyton Road) – Baileyton, Airport | Southern terminus of SR 172 |
| Tennessee | Greene | Greeneville | 68.0 | 109.4 | US 11E Bus. north (SR 107 / Tusculum Boulevard) | North end of US 11E Bus. overlap |
| Tennessee | Greene | Greeneville | 68.4 | 110.1 | US 11E Bus. south (SR 350 / West Summer Street) / SR 350 north | South end of US 11E Bus. overlap |
| Tennessee | Greene | Greeneville | 68.5 | 110.2 | SR 350 south (McKee Street) | South end of SR 350 (hidden) overlap |
| Tennessee | Greene | Greeneville | 69.5 | 111.8 | SR 70 / SR 107 west (Asheville Highway) | West end of SR 107 (hidden) overlap |
| Tennessee | Greene | Greeneville | 71.3 | 114.7 | SR 349 west (Warrensburg Road) | Eastern terminus of SR 349 |
| Tennessee | Cocke | Parrottsville | 87.3 | 140.5 | SR 340 – Parrottsville, Del Rio | |
| Tennessee | Cocke | ​ | 91.6 | 147.4 | SR 160 north – Bybee | Southern terminus of SR 160 |
| Tennessee | Cocke | Newport | 93.7 | 150.8 | US 25 south / US 70 (SR 9 / Broadway Street) | South end of US 25 and east end of US 70 overlap |
| Tennessee | Cocke | Newport | 94.0 | 151.3 | US 25 north (SR 9) / US 70 west (SR 35) / SR 32 north (Broadway Street) | North end of US 25 / SR 32 and west end of US 70 overlap |
| Tennessee | Cocke | Newport | 95.5 | 153.7 | I-40 – Knoxville, Asheville | I-40 exit 435 |
| Tennessee | Cocke | ​ | 101.1 | 162.7 | SR 73 north (Wilton Springs Road) | North end of SR 73 (hidden) overlap |
| Tennessee | Cocke | Cosby | 106.0 | 170.6 | SR 339 west (Jones Cove Road) – Cherokee Hills | Eastern terminus of SR 339 |
| Tennessee | Cocke | Cosby | 106.2 | 170.9 | Foothills Parkway to I-40 | Western terminus of section 8A of the Foothills Parkway |
| Tennessee | Cocke | Cosby | 108.0 | 173.8 | SR 32 south | South end of SR 32 overlap |
| Tennessee | Sevier | Pittman Center | 119.9 | 193.0 | SR 416 north (Pittman Center Road) | Southern terminus of SR 416 |
| Tennessee | Sevier | Gatlinburg–Pittman Center line | 120.8 | 194.4 | SR 454 north (Buckhorn Road) | Southern terminus of SR 454 |
| Tennessee | Sevier | Gatlinburg | 126.1 | 202.9 | US 441 south / SR 73 Scenic west (Parkway/SR 71) – Great Smoky Mountains National Park | South end of US 441 overlap; eastern terminus of SR 73 Scenic |
| Tennessee | Sevier | Gatlinburg | 127.2 | 204.7 | Gatlinburg Parkway Bypass – Great Smoky Mountains National Park | No access from northbound US 441/US 321 |
| Tennessee | Sevier | Pigeon Forge | | | SR 449 north (Dollywood Lane) – Dollywood | Southern terminus of SR 449 |
| Tennessee | Sevier | Pigeon Forge | 134.5 | 216.5 | US 441 north (Parkway/SR 71) – Sevierville | North end of US 441 overlap |
| Tennessee | Sevier | Wears Valley | 142.9 | 230.0 | Foothills Parkway | Interchange; eastern terminus of western section of Foothills Parkway |
| Tennessee | Blount | Townsend | 149.4 | 240.4 | SR 73 Scenic east (East Lamar Alexander Parkway/SR 337) – Great Smoky Mountains National Park | Western terminus of SR 73 Scenic |
| Tennessee | Blount | Walland | 156.8 | 252.3 | Foothills Parkway – Top of The World, Chilhowee Lake, Great Smoky Mountains National Park Look Rock area | Interchange |
| Tennessee | Blount | Maryville | 166.7 | 268.3 | SR 447 north (Washington Street) to US 411 north | Southern terminus of SR 447 |
| Tennessee | Blount | Maryville | 167.4 | 269.4 | SR 336 south (Montvale Road) | Northern terminus of SR 336 |
| Tennessee | Blount | Maryville | 167.6 | 269.7 | US 411 (Broadway Avenue/SR 33) – Rockford, Madisonville | |
| Tennessee | Blount | Maryville | 168.7 | 271.5 | US 129 (SR 115) – Alcoa, Knoxville | |
| Tennessee | Blount | Maryville | 171.0 | 275.2 | SR 335 north (Old Glory Road) | North end of SR 335 overlap |
| Tennessee | Blount | Maryville | 171.6 | 276.2 | SR 335 south (William Blount Drive) | South end of SR 335 overlap |
| Tennessee | Blount | Friendsville | 176.1 | 283.4 | SR 333 north (Main Avenue) – Friendsville | Southern terminus of SR 333 |
| Tennessee | Loudon | ​ | 181.4 | 291.9 | SR 95 south (Lenoir City Road) – Greenback | South end of SR 95 (hidden) overlap |
| Tennessee | Loudon | ​ | 185.0 | 297.7 | SR 444 west (Tellico Parkway) – Tellico Village | Eastern terminus of SR 444 |
| Tennessee | Loudon | Lenoir City | 186.8 | 300.6 | US 11 (Broadway Street/SR 2) – Knoxville, Loudon, Farragut | |
| Tennessee | Loudon | Lenoir City | 189.5 | 305.0 | I-75 – Knoxville, Chattanooga | I-75 exit 81 |
| Tennessee | Loudon | Lenoir City | 190.3 | 306.3 | US 70 (Kingston Pike/SR 1) – Knoxville, Kingston | |
| Tennessee | Loudon | Lenoir City | 194.2 | 312.5 | I-40 / SR 95 north (White Wing Road) – Knoxville, Nashville, Oak Ridge | West end of SR 73 (hidden) and north end of SR 95 (hidden) overlap; I-40 exit 364 |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus Route transition Unopened |||||||

## Special routes
### Winnsboro business loop

U.S. Route 321 Business (US 321 Bus.) is a 4.350-mile (7.001 km) business route of US 321 that exists in Winnsboro Mills and Winnsboro, via Columbia Road and Congress Street. It was established around 1951 or 1952, when mainline US 321 was rerouted west, bypassing Winnsboro.

### Chester business loop

U.S. Route 321 Business (US 321 Bus.) is a 3.670-mile (5.906 km) business route of US 321 in the city of Chester. It traverses downtown Chester, via Columbia Street and Center Road. It was established between 1962 and 1964, when mainline US 321 was rerouted west, bypassing Chester.

### York business loop

U.S. Route 321 Business (US 321 Bus.) is a 2.500-mile (4.023 km) business route of US 321 in the city of York, utilizing Congress Street and Kings Mountain Street. It was established around 1957–1958, when mainline US 321 was rerouted west, bypassing York.

### Dallas–Hickory business loop

U.S. Route 321 Business (US 321 Bus) was established in June 1999, as a renumbering all of NC 155 and part of mainline US 321 in Catawba County. Traversing 37.2 miles (59.9 km) through Gaston, Lincoln and Catawba counties, it connects the cities and towns of Dallas, High Shoals, Lincolnton, Maiden, Newton, Conover and Hickory. The highway follows the original US 321 routing through that existed prior to 1994.

### Lincolnton alternate route

U.S. Route 321 Alternate (US 321A) was established 1956 when mainline US 321 was placed on new bypass east of downtown Lincolnton. It traversed along Aspen Street and around the Lincoln County Civil Court on Court Square Drive. In 1960 it was decommissioned, with Aspen Street becoming secondary roads.

### Granite Falls–Lenoir alternate route

U.S. Route 321 Alternate (US 321A) was established 1948 as a number swap with US 321 through downtown Lenoir. In 1957, US 321A was extended south, replacing mainline US 321 through Granite Falls and Hudson, ending at its current southern terminus north of the Catawba River. In June 1964, US 321A was placed on one-way splits through downtown Lenoir; northbound continued along Mulberry Street and West Avenue, southbound rerouted along Main Street and College Avenue. In September 2006, US 321A was rerouted to its current northern terminus, just south of downtown Lenoir, via McLean Drive. Its old alignment through downtown Lenoir was carried on by NC 90 until 2012, when it too was rerouted; the old alignment is now under city control.
Traversing through Granite Falls, Sawmills, Hudson and Lenoir US 321A has not changed much over the years. Predominantly a two-lane highway, it parallels a short line railroad and connects to several factories and downtowns.

### Lenoir alternate route

U.S. Route 321 Alternate (US 321A) was established 1941 as a new alternate route bypassing Lenoir. In 1948, it was replaced by mainline US 321.

### Blowing Rock business loop

U.S. Route 321 Business (US 321 Bus) was established 1960 as an upgrade to secondary roads through downtown Blowing Rock; which were originally part of mainline US 321 until about 1954, when it was moved onto a new bypass east. The highway traverses along Main Street and shares a concurrency with US 221 for 0.8 miles (1.3 km) on its northern section.

### Boone truck route

U.S. Route 321 Truck (US 321 Truck) redirects truckers traveling through the area to go south and around downtown Boone, via NC 105 and NC Highway 105 Bypass (SR-1107). The shares some overlap with US 221 Truck and complete overlap with US 421 Truck.

### Greeneville truck route

U.S. Route 321 Truck (US 321 Truck) redirects truckers traveling south on US 321 around downtown. It shares a concurrency with US 11E and SR 70. The route begins at US 11E/US 321 and ends 3.6 miles (5.8 km) later at US 321/SR 70.
The entire route is in Greeneville, Greene County.
| mi | km | Destinations | Notes |
| 0.0 | 0.0 | US 321 / SR 35 (West Main Street) / SR 70 south (Asheville Highway) / SR 107 (Asheville Highway / West Main Street) – Greeneville, Parrottsville, Newport, Del Rio, Asheville | Southern terminus of US 321 Truck and end SR 70 overlap |
| 1.0 | 1.6 | US 11E Bus. north (West Summer Street) / SR 350 south (West Summer Street) – Downtown Greeneville | Begin US 11E Business concurrency; Northern terminus of SR 350 |
| 1.2 | 1.9 | US 11E south / SR 34 south (West Andrew Johnson Highway) / Blue Springs Parkway – Mosheim, Bulls Gap, Morristown | Southern terminus of US 11E Business; Begin US 11E/SR 34 overlap |
| 1.7 | 2.7 | SR 70 north (Lonesome Pine Trail) – Romeo, Rogersville | End SR 70 overlap |
| 2.0 | 3.2 | SR 172 north (Baileyton Road) / WhiteHouse Road – Baileyton, Airport | Southern terminus of SR 172; Interchange |
| 3.4 | 5.5 | US 11E north / US 321 (North Main Street / East Andrew Johnson Highway) / SR 34 north (East Andrew Johnson Highway) / SR 35 south (North Main Street) – Jonesborough, Johnson City, Newport, Downtown Greeneville | End US 321 Truck |
| 3.6 | 5.8 | SR 93 north (Kingsport Highway) – Fall Branch, Kingsport | Southern terminus of SR 93 |
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus ||||