Before the construction of I-40, US 70 was the main east-west route through North Carolina. At a number of points, I-40 has been constructed deviating from US 70. For example, US 70 followed the route along the French Broad River through the Appalachian Mountains west of Asheville, while I-40 was built further south through the Pigeon River valley. US 70 also ran in the Piedmont from Statesville via Salisbury to Greensboro instead of via Winston-Salem. In eastern North Carolina, I-40 was built mostly parallel to US 117, which ran from Goldsboro to Wilmington.
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Planning
When the Interstate Highway system was created in 1956, I-40 served as an east-west route to Greensboro. East of Greensboro, I-85 was planned, but no Interstate Highway further along Durham and Raleigh to Wilmington was planned at the time. Planning for the eastern portion of I-40 did not begin until the 1960s. In the Federal-Aid Highway Act of 1968an extension of I-40 past Durham and Raleigh to Smithfield was included. It was planned that I-40 would run all the way to I-95. It was not until 1984 that an extension was included all the way to Wilmington, with the route not intersecting I-95 at Smithfield as previously planned, but more southwest at Benson. Of the coastal towns in the southeastern United States, Wilmington was one of the least important, with Interstate Highways planned to Savannah and Charleston, but not to Wilmington or Myrtle Beach.
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Construction history
Construction on I-40 began in downtown Winston-Salem in 1956 and was the first section of Interstate 40which was constructed. In 1992 this route would be replaced by a new bypass on the south side. Construction of I-40 took place primarily in western North Carolina in the 1960s. In 1960, the section double-numbered I-85 opened. The section through the Appalachian Mountains on the Tennessee border was 22 miles long and completed in 1968, it was the only highway east of the Mississippi River at the time to have tunnels. By 1974 the route as far as Raleigh had been completed, but had missing links in Durham that were not connected until the mid-1980s. Then construction began from Raleigh to Wilmington on the Atlantic coast. The last section of I-40 didn’t open until June 29, 1990 between Raleigh and Wilmington.
Opening history
The dates below are indicative, and are more of an impression of when a piece was completed, than exact opening dates.
| Van | Unpleasant | Length | Datum |
| Exit 131 | Exit 161 | 48 km | 00-00-1960 |
| Exit 85 | Exit 119 | 55 km | 00-00-1961 |
| Exit 131 | Exit 151 | 32 km | 00-00-1961 |
| Exit 180 | Exit 189 | 15 km | 00-00-1961 |
| Exit 27 | Exit 44 | 27 km | 00-00-1965 |
| Exit 64 | Exit 85 | 34 km | 00-00-1965 |
| Exit 189 | Exit 219 | 48 km | 00-00-1965 |
| Exit 0 | Exit 20 | 32 km | 00-00-1968 |
| Exit 44 | Exit 50 | 10 km | 00-00-1969 |
| Exit 20 | Exit 27 | 11 km | 00-00-1974 |
| Exit 151 | Exit 180 | 47 km | 00-00-1974 |
| Exit 219 | Exit 226 | 11 km | 00-00-1974 |
| Exit 260 | Exit 263 | 5 km | 00-00-1974 |
| Exit 270 | Exit 278 | 13 km | 00-00-1974 |
| Exit 279 | Exit 289 | 16 km | 00-00-1974 |
| Exit 119 | Exit 131 | 19 km | 00-00-1978 |
| Exit 289 | Exit 301 | 19 km | 00-00-1985 |
| Exit 398 | Exit 420 | 35 km | 00-00-1985 |
| Exit 278 | Exit 279 | 2 km | 00-00-1986 |
| Exit 301 | Exit 305 | 6 km | 00-00-1987 |
| Exit 263 | Exit 270 | 11 km | 00-10-1988 |
| Exit 306 | Exit 328 | 35 km | 00-10-1989 |
| Exit 328 | Exit 398 | 113 km | 29-06-1990 |
| Exit 188 | Exit 206 | 29 km | 00-11-1992 |
Arrange
The 2×4 lane I-40/85 at Burlington.
North Carolina is a fast-growing state, so several sections of I-40 have been widened. Most notable is the 35-mile double-numbering Interstate 85 between Greensboro and Hillsborough, which was immediately widened from 2×2 to 2×4 lanes in the 1990s. Work started in 1989, although work on most of the route did not start until after 1993. The widening was completed in 1996, costing $175 million at the time. At the time, this was one of the few rural stretches in the southeastern United States to have 2×4 lanes.
An eight-kilometer stretch between Raleigh-Durham International Airport and Wade Avenue on the west side of Raleigh already had 2×3 lanes before 1993, it may have been built directly with 2×3 lanes in 1972, or was later widened when Raleigh-Durham International Airport increased in importance in the late 1980s. In about 2000, this part was widened to 2×4 lanes. In 2004, the connecting section between NC-147 and Raleigh-Durham International Airport was widened to 2×4 lanes. At the same time, the 9-mile stretch of US 501 in Chapel Hill and NC-147 has been widened to 2×3 lanes.
The actual Raleigh bypass was presumably constructed directly with 2×3 lanes in 1985, with the eastern section between US 70 and I-440 presumably constructed directly with 2×4 lanes. Between 2013 and 2018 the ‘Fortify’ project was carried out in which I-40 was completely reconstructed. Although no real widening, several weaving strips have been laid and bridges widened.
In 1992, I-40 was rerouted at Winston-Salem over a route further south. The western half of this, west of I-74, was built directly with 2×3 lanes at the time. The original route of I-40 through Winston-Salem has since been renumbered as I-40 Business. In the second half of the 1990s, a 5-mile section west of Winston-Salem was widened to 2×3 lanes from I-40 Business / US 421 to Clemmons.
By 2002, the section between Business Route 40 in Kernersville and I-85 in Greensboro was widened from 2×2 to 2×4 lanes, except at the interchange with I-73 on the west side of Greensboro, which was already scheduled to be built. in a way that through traffic on I-40 would primarily use the Greensboro Urban Loop. Between 2003 and 2007, the interchange between I-40 and I-73 was constructed so that the main carriageway from I-40 merges with the Greensboro Beltway.
In 2006, a small portion of I-40 on the west side of Asheville was widened from 2×2 to 2×4 lanes, then extended a few more miles west of its junction with US 19 in 2008. This created a more gradual merging and splitting of traffic west of the interchange with I-26.
Between 2012 and 2017, the interchange with I-77 at Statesville was reconstructed. Originally this was a cloverleaf with no shunting lanes along both I-40 and I-77. The interchange has been converted to a clover turbine with a new arc for traffic from Charlotte to Asheville, a short section of I-40 long Statesville has been widened with a short parallel structure and a diverging diamond interchange at the junction with US 21.
South of Raleigh, I-40 was congested by burgeoning Wake County suburbs and traffic to the coast at Wilmington. That’s why, between 2018 and 2022, a $330 million 12-mile stretch from I-440 in Raleigh to NC-42 at Clayton has been widened from 2×2 to 2×4 lanes.
Beginning in late 2021, a 17-kilometer stretch between the junction with I-85 and US 15/501 in Chapel Hill has been widened from 2×2 to 2×3 lanes.
Traffic intensities
I-40 on the west side of Raleigh.
The intensities increase from 22,000 at the border with Tennessee to 51,000 just before Asheville. At Asheville itself, this is a maximum of 78,000 vehicles per day. Between Asheville and Winston-Salem there are about 35,000 to 45,000 vehicles per day. In Winstom-Salem, a maximum of 98,000 vehicles per day drive near the center. At Greensboro, the road is somewhat busier, with a maximum of 131,000 vehicles per day. The double numbering with the I-85 counts about 90,000 to 110,000 vehicles per day, which is a lot for an interurban highway. At Durham, up to 163,000 vehicles per day and 153,000 in Raleigh. South of Raleigh, intensities drop to just above 20,000 vehicles, with a final peak of 30,000 vehicles in Wilmington.
Lane Configuration
I-40 at Warsaw in eastern North Carolina.
| Van | Unpleasant | Lanes | Comments |
| Exit 0 | Exit 183 | 2×2 | |
| Exit 183 | Exit 196 | 2×3 | Winston-Salem |
| Exit 196 | Exit 206 | 2×2 | |
| Exit 206 | Exit 212 | 2×4 | Greensboro |
| Exit 212 | Exit 227 | 2×3 | Greensboro |
| Exit 227 | Exit 259 | 2×4 | double numbering with I-85 |
| Exit 259 | Exit 270 | 2×2 | Durham |
| Exit 270 | Exit 279 | 2×3 | Durham |
| Exit 279 | Exit 289 | 2×4 | Raleigh |
| Exit 289 | Exit 297 | 2×3 | Raleigh |
| Exit 297 | Exit 312 | 2×4 | Raleigh |
| Exit 312 | Exit 420 | 2×2 |
