The official designation of the route runs 0.78 miles (1.26 km) along Terminal Avenue between DE 9 and the Port of Wilmington, interchanging with I-495.

Christina Avenue originally became a state highway in the 1920s, serving as part of US 40 that connected to a ferry across the Delaware River to Penns Grove, New Jersey.

At this point, DelDOT officially marks the end of DE 9A, but signage shows it turning north onto Christina Avenue.

[2][4] DE 9A proceeds north-northwest as a two-lane road, passing through more industrial areas and crossing under I-495 again, this time underneath the I-495 bridge over the Christina River.

[7] Christina 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.