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 , 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 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 , facing south before it was rerouted. 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 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 stretch near Walland. ==History==