Maryland Route 646 (MD 646) is a state highway in the U.S. state of Maryland. Known as Prospect Road, the state highway runs 3.31 miles (5.33 km) from MD 543 near Ady north to MD 136 at Prospect. MD 646 was constructed as a section of MD 543 in the early 1930s. That section of MD 543 and the road originally marked as MD 646 swapped numbers by 1946.
Route description 
MD 646 begins at an intersection with MD 543 (Ady Road) in the hamlet of Emory Church near Ady. Cherry Hill Road heads west from the other side of MD 543 as a county highway toward Rocks State Park. MD 646 heads northeast through farmland. After crossing Broad Creek, the state highway passes through the Mill Green Historic District, where it intersects Mill Green Road. MD 646 crosses Broad Creek again and continues to its northern terminus at MD 136 (Whiteford Road) in the hamlet of Prospect. Prospect Road continues north as a county highway toward the Pennsylvania state line.
The portion of modern MD 646 from MD 543 at Emory Church to just north of Mill Green was constructed in 1933 as the northern end of MD 543. MD 646 was originally assigned to the section of MD 543 between Emory Church and Pylesville, which was constructed around 1938. By 1946, MD 646 and MD 543 had swapped to their present routes north from Emory Church toward Mill Green and Pylesville, respectively. MD 646 was extended north to MD 136 in 1950.
Junction list 
The entire route is in Harford County.
See also 
- ^ a b c Highway Information Services Division (2011). Highway Location Reference. Maryland State Highway Administration. Retrieved 2011-03-01.
- ^ Google Inc. Google Maps – Maryland Route 646 (Map). Cartography by Google, Inc. http://maps.google.com/maps?f=d&source=s_d&saddr=MD-646%2FProspect+Rd&daddr=MD-646%2FProspect+Rd&hl=en&geocode=FeYKXQIdmDVz-w%3BFf2gXQIdt7Zz-w&mra=ls&sll=39.654242,-76.332879&sspn=0.00755,0.01929&ie=UTF8&t=h&z=13. Retrieved 2010-06-07.
- ^ Byron, William D.; Lacy, Robert (December 28, 1934). Report of the State Roads Commission of Maryland (1931–1934 ed.). Baltimore: Maryland State Roads Commission. p. 339. Retrieved 2011-03-01.
- ^ Maryland Geological Survey. Map of Maryland Showing State Road System: State Aid Roads and Improved County Road Connections (Map) (1933 ed.).
- ^ Beall, J. Glenn; Jarboe, Elmer R.; Obrecht, George F., Sr. (March 4, 1939). Report of the State Roads Commission of Maryland (1937–1938 ed.). Baltimore: Maryland State Roads Commission. p. 117. Retrieved 2011-03-01.
- ^ Maryland State Roads Commission. General Highway Map: State of Maryland (Map) (1939 ed.).
- ^ Maryland State Roads Commission. Maryland: Official Highway Map (Map) (1946–47 ed.).
- ^ Maryland State Roads Commission. Maryland: Official Highway Map (Map) (1950 ed.).
External links 
Route map: Google / Bing