In 1951, a second bridge over the railroad was completed in north Salisbury and US 13 north of Zion Road was relocated and expanded to a divided highway. US 13's present divided highway bypass of Delmar was completed in 1954 concurrent with the adjacent section of the route in Delaware bypassing Laurel and Seaford. The former alignment through Delmar was designated as US 13 Alt. between 1954 and 1957 and became MD 675 by 1983. US 13 from Princess Anne to College Avenue in Salisbury was also dualized between 1954 and 1956. In 1957, US 13 was widened into a divided highway between the Virginia border and Pocomoke City. US 13's bypass of Princess Anne was constructed between 1957 and 1959. MD 675 was marked on the former alignment through Princess Anne by 1978. In 1963, US 13 was rerouted to bypass Pocomoke City to the northeast, with the former alignment through Pocomoke City becoming MD 675, which was replaced by US 13 Bus. in 1994. US 13 was expanded to a divided highway from the southern end of the Princess Anne bypass south past Kings Creek in 1962, south through Westover in 1963, and south to about north of MD 667 in 1964. The Princess Anne bypass was expanded to a divided highway in 1965. US 13's expansion to a four-lane highway in Maryland was completed in 1966 when the federal highway was expanded to a divided highway from north of MD 667 south past West Pocomoke to the southern end of the Pocomoke City bypass.