MD 108 heads southeast as a continuation of Waterloo Road toward Jessup and west as Old Annapolis Road, which provides access to Howard High School and ramps to and from eastbound MD 100.

MD 104 reduces to two lanes and passes through a suburban area on the southern edge of Ellicott City, where the highway reaches its northern terminus at MD 103 (Montgomery Road), which heads southeast toward Elkridge and northwest toward downtown Ellicott City.

[1][2] Waterloo Road was built as a macadam road in 1932 from U.S. Route 1 (US 1) in Jessup north to MD 103 in Ellicott City; the highway was designated MD 531.

[6] Old Annapolis Road was designated MD 539 in 1956; that highway became part of an extended MD 108 in 1960 when US 29 was moved to Columbia Pike from Silver Spring to Ellicott City.

[7][8] After MD 175 was rerouted along Little Patuxent Parkway (now named Rouse Parkway) from west of Interstate 95 (I-95) to Columbia Town Center around 1977, MD 108 was extended east to its present terminus near I-95.