Maryland Route 166

Maryland Route 166
Maryland Route 166 highlighted in red
Route information
Maintained by MDSHA
Length:	2.71 mi (4.36 km)
Existed:	1927 – present
Major junctions
South end:	I-195 in Arbutus
	MD 372 in Catonsville
North end:	MD 144 in Catonsville
Location
Counties:	Baltimore
Highway system
Maryland highway system Interstate US State Scenic Byways ← MD 165 MD 168 →

Maryland Route 166 (MD 166) is a state highway in the U.S. state of Maryland. The state highway runs 2.71 miles (4.36 km) from Interstate 195 (I-195) in Arbutus north to MD 144 in Catonsville. MD 166 consists of two sections: a short freeway section that serves as a northern continuation of I-195 and provides access to the University of Maryland, Baltimore County (UMBC), and a segment of Rolling Road, a major north–south highway in western Baltimore County. Rolling Road dates to the colonial era as a highway used to transport tobacco from plantations to river ports. North Rolling Road, which connects Catonsville with Woodlawn and Milford Mill, has always been a county highway. South Rolling Road was constructed as a state highway by the early 1920s between what were to become U.S. Route 1 and US 40. Parts of South Rolling Road were transferred to county maintenance after they were severed by the construction of I-95 and a freeway relocation of the southern end of MD 166 in the early 1970s.

MD 166 begins as a continuation of the four-lane Metropolitan Boulevard freeway at the northern terminus of I-195 just north of the Interstate's interchange with I-95. The highway passes under Selford Road and has a partial interchange with UMBC Boulevard that allows access to the UMBC campus to and from the south. MD 166 curves northwest over the ramp from southbound UMBC Boulevard and the freeway's carriageways split around a park and ride facility as the freeway terminates at South Rolling Road. MD 166 continues north along two-lane South Rolling Road. The highway meets the western end of MD 372 (Wilkens Avenue) and passes between Rolling Road Golf Course on the east and the Catonsville Campus of the Community College of Baltimore County to the west. MD 166 temporarily expands to four lanes between Valley Road and Bloomsbury Avenue, between which the highway passes Catonsville High School. The highway narrows and passes along the edge of the Central Catonsville and Summit Park Historic District before veering north at Hilton Avenue and reaching its northern terminus at MD 144 (Frederick Road) west of downtown Catonsville.