MD 28 originally followed Baltimore Road between downtown Rockville and east of Rock Creek. Between 1940 and 1944, MD 28 was placed on a new grade-separated crossing of the Metropolitan Branch along Veirs Mill Road, then north on First Street to Baltimore Road. MD 28 was rolled back from Ashton to Norbeck between 1944 and 1946. In 1969 or 1970, the controlled access portion of US 15 north of Point of Rocks was completed. As a result, MD 85 was assigned to the old route of US 15 north of Tuscarora and MD 28 was extended west to its current terminus in Point of Rocks. Also in 1970, the bypass of Baltimore Road in eastern Rockville was under construction. In 1981, MD 28 was made a divided highway between downtown Rockville and Baltimore Avenue west of Rock Creek. In 1982, the divided highway was extended from Baltimore Avenue east of Rock Creek to MD 97.