The Salem Parkway is an 18.5-mile-long (29.8 km) freeway in the U.S. state of North Carolina, serving the city of Winston-Salem and the town of Kernersville. It is signed as U.S. Route 421 (US 421) for its entire length, though it is also concurrent with US 158 in downtown Winston-Salem and North Carolina Highway 150 (NC 150) between Winston-Salem and Kernersville. Originally known as the East–West Expressway, it was designated as part of Interstate 40 (I-40) and opened in 1958, becoming the first section of Interstate Highway in the state. I-40 was rerouted onto a new alignment bypassing Winston-Salem and Kernersville in 1992, at which time the road was designated Interstate 40 Business, nicknamed Business 40.

Beginning in November 2018, a 1.2-mile-long (1.9 km) section of the freeway in downtown Winston-Salem between Peters Creek Parkway (NC 150) and the John Gold Memorial Expressway (US 52) was closed for reconstruction to rebuild the substandard roadway, exit and entrance ramps, and bridges. The section east of Main Street reopened August 30, 2019. As part of the project, the Business 40 designation was decommissioned and replaced with the name Salem Parkway, which had been chosen by popular vote in 2016. This included changing guide signs to include the new name, as well as renumbering exits to follow the mileage of US 421. The name change went into effect on February 2, 2020, when the road reopened, though signage outside of the project area had been changed in late December 2019.

The Salem Parkway runs east–west through Winston-Salem and Kernersville, though it is designated on signs as the north–south US 421, with north on the signage aligning to west, and vice versa.

The parkway begins on US 421 at Exit 238, the interchange with I-40 in Winston-Salem. The route runs northeast carrying US 421, meeting the Silas Creek Parkway (NC 67) at a cloverleaf interchange before reaching an interchange with Stratford Road (US 158). From here, the parkway turns east concurrent with US 158, continuing east and joining NC 150 at Peters Creek Parkway. In downtown Winston-Salem, the Salem Parkway meets Marshall Street and Cherry Street before passing under the Strollway. A half-interchange allows access to and from the one-way northbound Main Street, with only a westbound off-ramp and eastbound on-ramp. The parkway intersects the John Gold Memorial Expressway (US 52/NC 8, though NC 8 is not signed at this interchange) at a cloverleaf interchange and meets Martin Luther King Jr. Drive immediately after.

Leaving the downtown Winston-Salem area, US 158 exits the Salem Parkway onto Reidsville Road at a partial interchange, with the parkway continuing east concurrent with US 421 and NC 150. Entering Kernersville, the parkway comes to a partially built interchange with the under-construction Winston-Salem Northern Beltway (NC 74). Continuing through the town, the Salem Parkway meets South Main Street and then NC 66. The route then passes a diamond interchange with Macy Grove Road with NC 150 exiting the parkway, in which The Salem Parkway exits Forsyth County shortly after. This happens right before ending at a half-interchange with I-40 south of Colfax, with only an eastbound entrance and westbound exit on I-40. US 421 continues on I-40 toward Greensboro.

After the consolidation of Winston and Salem in 1913, the combined city was not only a merger of local government but a joining of two different road systems. By the 1940s, Winston-Salem grew to become the largest manufacturing hub in the state, thanks to companies like R. J. Reynolds Tobacco Company and the P.H. Hanes Knitting Company; while multiple highways connected the city, there was no road that directly went from one end to the other without making turns and as a result traffic congestion was a constant in the downtown area. From 1946 to 1956, various traffic pattern studies were performed and plans created that reshaped the city for the next fifty years.

In 1954, Winston-Salem gave the state $1 million to buy right-of-way for what was called the East–West Expressway; construction began that same year. Though it was planned to become a new routing of US 158, that changed two years later, when the Federal Aid Highway Act of 1956 was passed and North Carolina was allocated 714 miles (1,149 km) for their share of the Interstate Highway System; 219 miles (352 km) was subsequently allocated for a route from the Tennessee state line, through Asheville and Winston-Salem, to Greensboro. With the designation of I-40, the East–West Expressway would become the first completed section of Interstate in the state.

On January 6, 1958, the first 1.2-mile-long (1.9 km) section of the East–West Expressway was opened between Cloverdale Avenue and Main Street. Because of the novelty, local newspapers ran a series of stories and diagrams on how to use the expressway, educating the public on how on-ramps and off-ramps work. Designated as I-40, the expressway soon ran concurrently with US 158 in 1959, from Stratford Road to Marshall (westbound) and Cherry (eastbound) streets. In 1960, the expressway was extended west into Yadkin County, at NC 801, and east to Reidsville Road. In 1961, US 421 was rerouted from Pfafftown and downtown Winston-Salem onto new freeway that connected directly with the expressway, then continued easterly running concurrently with I-40. In 1962, US 158 was realigned to continue along the expressway to Reidsville Road, its former alignment became US 158 Business (decommissioned in 1970). East of Reidsville Road, I-40/US 421 was extended onto new freeway to Kernersville, where it then linked with second built section of I-40 (late 1958) and continued towards Greensboro.

Interstate 40 Business
Location	Winston-Salem–Colfax, NC
Length	18.5 mi (29.8 km)
Existed	1992–2020
History	Briefly extended through Greensboro in 2008

After 1958, the East–West Expressway segment of I-40 changed little while Interstate standards have changed considerably in regards to safety and faster speeds. In the 1980s, a study with the city and state concluded that construction of a new route was preferable to widening and modernizing the freeway through Winston-Salem. The state therefore lobbied the Federal Highway Administration (FHWA), arguing that since this section predated the 1956 Act, it never received federal highway dollars for its development and construction, thus I-40 was incomplete in Winston-Salem. In October 1988, they were able to convince the FHWA, and Governor James G. Martin announced federal approval of $114.1 million for I-40 to be relocated onto new bypass south of Winston-Salem. In November 1992, the 20.89-mile (33.62 km) Winston-Salem Bypass was completed and opened; I-40 was officially rerouted at that time and a new designation was given to the East–West Expressway, Interstate 40 Business.

Since its opening in 1960, the Hawthorne Curve, a 10° S-curve overpass of Hawthorne Road, became an infamous accident-prone location; typically speed related, cars and trucks wrecking against the curve and in some cases jumping the guard rail and falling 35 feet (11 m) off the overpass. Blame for the curve mostly fell on then Winston-Salem Mayor Marshall Kurfees, who is believed to have ordered the curve to protect political allies who owned businesses on Hawthorne Road and First Street. Kurfees spent the rest of his life denying the allegation, stating that the engineers designed it while he had no input to the project. Over the years, several studies were done and various little fixes were made to improve the situation including a reduced 45-mile-per-hour (72 km/h) speed zone, better guardrails and the installation of blinking lights and flashing warning signs. In January 1998, the first major improvement in 40 years started with the realignment of Hawthorne Curve. At a cost of $26 million, construction lasted for two years building a new overpass and reshaping the sharp curve to a more gentle one. It was completed seven months early in the middle of 2000.

In February 2008, I-40 was rerouted onto new freeway south of Greensboro, becoming part of the Greensboro Urban Loop. The old route through Greensboro became an extension of I-40 Business, with a six-mile (9.7 km) hidden concurrency along I-40/US 421, between exits 206 and 212. This extended the route 20 miles (32 km), ending at a new terminus with I-85/I-40, near McLeansville.

However, NCDOT officials received many complaints by local residents and motorists on the confusion between the new I-40 and I-40 Business. Another issue was that funding for construction and repairs on the old route was slashed since it was no longer designated as an Interstate (Interstate business routes are not officially part of the Interstate Highway System) On September 12, 2008, with permission from the FHWA, I-40 was moved back to its old route through Greensboro, decommissioning Business 40 through Greensboro.

Construction began in June 2013 on the first phase of a project to extend Macy Grove Road around the east side of Kernersville. Macy Grove Road, which previously passed over Business 40 with no interchange and ended at Old Greensboro Road, was extended to a temporary terminus at a connector to East Mountain Street, with a diamond interchange built connecting it to Business 40. The extension and interchange opened in May 2015, at which point the former partial interchange with East Mountain Street immediately east of the NC 66/NC 150 interchange was closed and demolished and the westbound roadway through the former interchange realigned closer to the eastbound roadway. In October 2020, NC 150 was rerouted onto Macy Grove Road from the Salem Parkway interchange to the Main Street intersection as Macy Grove Road was extended north from its section built in 2015.

In 2006, the North Carolina Department of Transportation (NCDOT) decided to rebuild the freeway between Fourth Street and Church Street, which covers most of the original 1.2-mile-long (1.9 km) section of the East–West Expressway from 1958. For the next ten years, NCDOT made several studies and a series of public meetings before awarding a design-build contract with Flatiron Constructors, Inc./Blythe Development Company Joint Venture and HDR Engineering, Inc., in September 2016, to complete the final design and construct the project. Considered as a $100 million do-over, the project included: replacing the existing roadway pavement, modernizing entrance and exit ramps, replacing nine vehicular bridges, adding two pedestrian bridges, lengthening the acceleration and deceleration lanes between ramps and widening existing roadway shoulders and adding new ones.

NCDOT had also decided that once construction was completed, that I-40 Business would be decommissioned and a new name would be given to the freeway alongside the existing US 421 designation. The rationale was the continued confusion locals and travelers have between I-40 and I-40 Business. In November 2015, the residents of Winston-Salem metro area were allowed to submit a nomination for a new name, with a January 30, 2016, deadline. A selection committee, which included appointments from Winston-Salem and Kernersville, whittled the list to just four for another public vote. The eventual four finalist names were: Golden Leaf Parkway, alluding to the region's tobacco-growing and processing heritage; Innovation Highway, showing the high-tech aspirations of the area; Piedmont Corridor, identifying geographic location in a highly developed part of the state, and Salem Parkway, which refers to the Moravian settlement founded in 1766. On October 21, 2016, Governor Pat McCrory announced, at the project's ground breaking event, the new name of the freeway as the Salem Parkway; which was the overwhelming favorite, receiving 53% of the vote. This name change took place when the highway reopened on February 2, 2020, though new signs would show the Salem Parkway name once installed.

First phase of construction was focused on and around Peters Creek Parkway (NC 150), which included lowering the freeway to establish a minimum vertical clearance of 17 feet (5.2 m) at the new Fourth Street two-lane bridge and 17.5 feet (5.3 m) at the new seven-lane Peters Creek Parkway bridge. After two years of intermittent closures, the new Peters Creek Parkway bridge was opened on November 12, 2018. On November 17, the second phase began with the complete shutdown of Business 40 between Peters Creek Parkway and John Gold Memorial Expressway (US 52/US 311/NC 8); three alternate routes were set up through the downtown area for locals while travelers are encouraged to remain on mainline I-40.

During construction, Business 40 was lowered to establish a minimum vertical clearance of 17 feet (5.2 m) for the new Marshall, Cherry, Main and Church Street bridges; Spruce Street bridge was removed and Liberty Street changed from an underpass to an overpass as a result. The Broad Street interchange was permanently closed and removed, the Cherry Street interchange will be modified with Marshall Street, and the Main Street interchange was modified to have only a southbound on-ramp and a northbound off-ramp. Two pedestrian bridges will also be completed, one of which will replace Green Street Bridge, and a Strollway Bridge adjacent to Liberty Street.

On August 30, 2019, the section east of Main Street was opened. Reconstruction of the downtown segment was completed February 2, 2020.

Exit numbers were renumbered to reflect U.S. 421's milemarkers.

County	Location	mi	km	Old exit	New exit	Destinations	Notes
Forsyth	Winston-Salem	0.00	0.00	—	—	US 421 north – Yadkinville	Continuation as US 421
				1	238	I-40 – Greensboro, Statesville	Westbound left exit
		1.63	2.62	2 A-B	237A-B	NC 67 east (Silas Creek Parkway south) – Forsyth Tech NC 67 west (Silas Creek Parkway north) – Wake Forest University, LJVM Coliseum
		2.42	3.89	3A	236	Knollwood Street
		2.88	4.63	3 B-C	235	US 158 west (Stratford Road)	West end of US 158 overlap; signed Exit 235A (Stratford Road north) and 235B (US 158 west/Stratford Road south) from westbound Salem Parkway
		3.45	5.55	4A	234C	Cloverdale Avenue
		3.79	6.10	4B	234B	West First Street / Hawthorne Road	Westbound exit and eastbound entrance
		4.16	6.69	5A	234A	NC 150 west (Peters Creek Parkway) – Truist Stadium	West end of NC 150 overlap
		4.51	7.26	5B	—	Broad Street	Permanently closed as of November 2018
		4.81	7.74	5C	233B	Cherry Street / Marshall Street	To Convention Center; Cherry Street signed indirectly from eastbound; Marshall Street signed indirectly from westbound
		5.00	8.05	5D	233A	Main Street	Westbound exit and eastbound entrance; to Old Salem and Salem College
		5.61	9.03	6A-B	232B-C	US 52 south / NC 8 south (John Gold Memorial Expressway) – Lexington US 52 north / NC 8 north (John Gold Memorial Expressway) – Mount Airy, Airport	NC 8 unsigned on guide signs; Smith Reynolds Airport signed as "Airport"
		5.88	9.46	6C	232A	Martin Luther King Jr. Drive	To Winston-Salem State University
		6.97	11.22	7	231	Lowery Street / Fifth Street	Eastbound Lowery Street, westbound Fifth Street
		7.86	12.65	8	230	US 158 east (Reidsville Road) – Walkertown, Reidsville	East end of US 158 overlap; eastbound exit and westbound entrance
		9.66	15.55	10	228	Linville Road
	Kernersville	11.66	18.76	—	227	NC 74 (Winston-Salem Northern Beltway) to US 311	Opened to traffic on September 4, 2020
		13.84	22.27	14	224	South Main Street – Kernersville
				15	222	NC 66 – Kernersville, Walkertown
		15.60	25.11	16	—	Mountain Street – Colfax	Permanently closed as of May 2015
		16.56	26.65	17	221	NC 150 east (Macy Grove Road) – Oak Ridge	East end of NC 150 overlap
Guilford	Colfax	18.50	29.77	—	—	I-40 east / US 421 south (Fordham Boulevard) – Greensboro	Continuation as I-40 / US 421
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Closed/former       Concurrency terminus       Incomplete access

• Media related to Interstate 40 Business (North Carolina) at Wikimedia Commons
• Media related to Salem Parkway at Wikimedia Commons
• Business 40 Home Page