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.

[7] 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.

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.

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.

[10][11] 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.

[13] 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.

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.

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 downtown Winston-Salem.

[16][17] During the end of 1992, the 20.89-mile (33.62 km) stretch 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.

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.

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.

[32] 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.

[33] 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.

[35][36] 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.