The first non-concurrent portions of Route 54 to be numbered were in Maryland in 1939, when MD 467 was marked on the portion around Mardela Springs and MD 455 was marked on the portion around Delmar, which extended from where Waller Road fully enters Maryland east to Brittingham Road. The portion of road between Brittingham Road and MD 353 was county-maintained. MD 455 was extended east from Brittingham Road to DE 26/MD 353 in 1958. In 1968, DE 32 was assigned to the entire highway within Delaware; the Maryland sections were still marked as MD 467 and MD 455. The whole highway was marked as Route 54 in 1969. In addition to the concurrencies with DE 26 and DE 30, Route 54 has been concurrent with DE 20. DE 20 was extended east of Dagsboro to terminate in Fenwick Island along with Route 54 by 1994. DE 20's eastern terminus was rolled back to its present location in 2005. Despite this, some DE 20 shields are posted along Route 54 between that route's eastern terminus and Fenwick Island.