Much of DE 9 is designated as part of the Delaware Byways system. From the southern terminus north to New Castle, DE 9 is designated as part of the Delaware's Bayshore Byway, a road that is noted for following the Delaware River and Delaware Bay shoreline. The byway continues south past the terminus of DE 9 toward Lewes. The sections of the route between DE 299 east of Odessa and 7th Street southwest of New Castle, Wilmington Road north of New Castle and A Street in Wilmington, and along 4th Street in Wilmington between Swedes Landing Road and US 13 Bus. and Market and West streets are part of the Harriet Tubman Underground Railroad Byway. The section of DE 9 between US 13 Bus. and Van Buren Street in Wilmington is part of the Washington–Rochambeau Revolutionary Route, a National Historic Trail. DE 9 has an annual average daily traffic count ranging from a high of 20,160 vehicles at the intersection with the northern terminus of DE 9A to a low of 412 vehicles at the border between Kent and New Castle counties. The portion of DE 9 between DE 141/DE 273 and East 6th Street in New Castle is part of the National Highway System.