Maryland Route 100 is a major east–west highway connecting U.S. Route 29 in Ellicott City and MD 177 in Pasadena. MD 100 also connects to Interstate 95 (I-95), US 1, the Baltimore–Washington Parkway, and I-97. The highway connects Howard County to the west with Anne Arundel County and the Chesapeake Bay to the east. MD 100 also provides access to the Baltimore–Washington International Airport (BWI) and the Arundel Mills shopping mall.

Maryland Route 177 is a state highway in the U.S. state of Maryland. Known as Mountain Road, the highway runs 10.92 miles (17.57 km) from MD 2 in Pasadena east to Gibson Island. MD 177 serves as an arterial highway through Pasadena, Jacobsville, and the Lake Shore area of northeastern Anne Arundel County. The highway is paralleled by MD 100 through Pasadena and Jacobsville. MD 177 originally began near what is now its western intersection with MD 648, which was originally part of MD 2. A short section of the highway was built in Pasadena in the early 1910s. MD 177 was extended east through Jacobsville in the early 1920s and to Gibson Island in the late 1920s. The highway was extended west in the late 1930s after MD 2 was relocated to its present four-lane divided highway. A freeway section of MD 177 was constructed between MD 3 in Glen Burnie and MD 2 in the mid-1960s; the freeway was renumbered MD 100 when that highway was completed from Pasadena to Jacobsville in the early 1970s. Congestion east of MD 100 led to the addition of a reversible lane in 1999.