Interstate 540 (North Carolina)

Interstate 540 (I-540) and North Carolina Highway 540 (NC 540), also known as the Raleigh Outer Loop, is a partially-completed beltway around the city of Raleigh, North Carolina, United States. When complete, it will fully encircle the city and nearby suburbs, meeting its parent route of I-40 in two locations. The first 25.84-mile (41.59 km) section from Durham to Knightdale is an Interstate Highway, and the remaining 32.9-mile (52.9 km) section from Garner to Durham is a North Carolina state highway.

The first section of I-540 runs from I-40 near the Raleigh–Durham International Airport to I-87/U.S. Highway 64 (US 64)/US 264 south of Knightdale. The route opened in January 2007, and was intended to be renumbered to I-640 and an Interstate highway in full when completed. The NCDOT decided against both when it became financially unfeasible to construct the entire route with public funds within a reasonable timeframe.

The remaining portion of the route (approximately two-thirds of the total completed mileage) is a toll road (part of the Triangle Expressway) that has been constructed as a North Carolina state highway. The first section of NC 540 was opened in July 2007, extending westward from the western terminus of I-540. Further extensions have carried NC 540 around the western side of Wake County to its current southwestern terminus south of Apex; an extension to Garner was scheduled to open in late-August 2024, but was delayed to late-September 2024. The final project planned to complete the eastern leg from Garner to Knightdale under the same toll system also began construction in 2024 with a completion date of 2028.