State Route 100 (SR 100) is a primary state highway in the U.S. state of Virginia. The state highway runs 53.31 miles (85.79 km) from U.S. Route 221 (US 221) in Hillsville north to SR 61 in Narrows. SR 100 is one of the major highways of the New River Valley, connecting Narrows and Pearisburg in Giles County with Dublin, Pulaski (via US 11), and Interstate 81 (I-81) in Pulaski County.