Green 40 carries four lanes in its entirety, and U.S. 421 is signed over its entire length. The road has had a few different names and numbers over the years. Some names include the East- West Parkway, the Interstate Expressway and the East- West Expressway. (The Durham Freeway was also once called the East- West Expressway, too.) Green 40's official numerical designation is either "I-40 Business" or "Business Loop 40".

By early 1960, the expressway was finished east of downtown W-S to the U.S. 158 exit (Reidsville Road). By 1962, all of the eventual Green 40 was finished, from the split with U.S. 421 on the west side of town east into Guilford County. 

Once the Downtown Expressway was finished, it was signed as both U.S. 421 and 158, in addition to I-40, entirely through downtown W-S. Before the early 1960s, 421 had approached downtown W-S from the northwest along Reynolda Road. Eastbound 158 diverged from the freeway at Reidsville Road, then as now, and for many years "eastbound" 421 left the freeway at the Colfax exit (modern exit 16). In 1997, 421 was rerouted onto the freeway from the Colfax exit all the way east to Greensboro. 

In late 1992, the Downtown Expressway was finally (after 35 years) bypassed by a new stretch of I-40 south of W-S. The Expressway at this time was redesignated as Green 40. Green 40 would keep I-40's old exit numbers (in the 190s and low 200s) for at least another year. Eventually the exits were renumbered, starting with 1 on the west side, in the mid-1990s. 

If you like your freeways with a lot of character, though, Green 40's time is running out. Funding is in place to rehabilitate the entire road. Two separate projects totaling $66 million will provide for new bridges, pavement and safety improvements. Construction on the western half of the freeway (project U-2827) will last until at least 2005. Further east on Green 40, work will be spread out longer (project R-952), starting in 2002 at the earliest and lasting beyond 2008. At least one on-ramp downtown (from Main Street) has been closed permanently. Neither project explicilty mentions adding lanes. 

Renumber, please. Green Interstates are too bush-league for a city like W-S, and North Carolina already has too many "Business" and "Bypass" routes lying around. One possibility is to simply take down all the Green 40 signs and call the freeway U.S. 421, except that 421 should be signed north-south and the freeway runs east-west. A better idea is to sign the freeway as a 3-digit interstate once upgrades to the road are complete. It could be called I-840, but that's the only even x40 left for the state to use, so 840 should be conserved. Instead, why not sign the Downtown Expressway as I-274? There's no better way to flaunt I-74 than to name a 3di after it.