 What is now DE 9A was a county road by 1920 . By 1924 , the Christiana Avenue portion of the route was constructed as a state highway . Christiana Avenue became a portion of US 40 in 1926 , running from US 13 to a ferry that went across the Delaware River to Penns Grove , New Jersey . By 1931 , US 40 was removed from this road . The road became the easternmost portion of DE 48 by 1936 , which crossed the Delaware River on the ferry to connect to New Jersey Route 48 in Penns Grove . DE 48 was removed from this road by 1952 after the ferry between Wilmington and Penns Grove was discontinued in 1949 . DE 9A was designated around 1971 onto its current alignment . 
