U.S. 521 extends just 3.72 miles north into Mecklenburg County, North Carolina from Indian Land, South Carolina. The route concludes at a cloverstack interchange joining Johnston Road with Interstate 485 in south Charlotte.
Constructed as a part of an $83.3-million contract to widen Interstate 485 from I-77 east to Rea Road, a flyover was built from U.S. 521 north to I-485 west (inner loop).1 Work was underway by Summer 2013 and the flyover completed by August 2014. The new ramp replaced a left turn for the Beltway west.
The historic alignment of U.S. 521 ran alongside U.S. 21 on Pineville Road and South Boulevard northward to Downtown Charlotte. By 1980, U.S. 21 was realigned onto an overlap with I-77. U.S. 21 remained along Pineville Road north to Woodlawn Road west, where it ended at I-77/U.S. 21.
U.S. 521 previously extended north along Billy Graham Parkway to Interstate 85 northeast of Charlotte Douglas International Airport (CLT). U.S. 521 was truncated southward to the Charlotte Beltway at Exit 61 with approval by the American Association of State Transportation and Highway Officials (AASHTO) on May 30, 2003. Prior to that, U.S. 421 was relocated from Pineville onto a shared alignment with Interstate 485.