MD 665 was originally assigned to Forest Drive. The road existed as a county highway between MD 387 and Bay Ridge Avenue, which was then designated
MD 181, by 1939. This highway was extended west to MD 2 (now MD 393) by 1946. MD 665 was assigned to the highway between MD 2 and MD 181 in 1950. MD 665 was routed along Chinquapin Round Road west of its rakish intersection with MD 387 and Neck Road east of MD 387. The whole highway was named Forest Drive in 1955, the same year the state highway was extended west to the present alignment of MD 2. The eastern end of MD 665 was relocated in 1964 to the current eastern end of Forest Drive at Bay Ridge Avenue and Hillsmere Drive. The old alignment along Forest Hills Avenue remained in the state highway system until 1972. MD 665 was relocated at its intersection with MD 387 to make the intersection less oblique in 1968. An old piece of Forest Drive in the southeast quadrant of the intersection is
MD 788A (Old Forest Drive). The original MD 665 was transferred from state maintenance to the city of Annapolis between 1987 and 1989. By 1989, modern MD 665, which was intended to mitigate congestion on the western part of Forest Drive, was under construction from US 50/US 301 southeast to MD 2. MD 665 opened from US 50/US 301 to MD 2 in 1991. The highway opened east to Forest Drive in April 1992. In October 1992, state officials named MD 665 for
Aris T. Allen, a doctor and former member of the
Maryland General Assembly who had died in 1991. When MD 665 was being planned in the early 1980s, Allen was instrumental in rerouting the highway to bypass an African-American neighborhood instead of slicing through and displacing its residents. ==Junction list==