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 road then leaves Kernersville at a diamond interchange with Macy Grove Road with NC 150 exiting the parkway. The Salem Parkway ends 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. History 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. East–West Expressway 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 for their share of the Interstate Highway System; 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 section of the East–West Expressway was opened, connecting 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.