MD 187 begins at an intersection with MD 355 (
Wisconsin Avenue) and westbound MD 410 (East–West Highway) next to the
Bethesda station along
Washington Metro's
Red Line in downtown Bethesda. The state highway heads northwest as a two-lane
one-way street to Woodmont Avenue. Southbound MD 187 traffic is required to turn north or south onto Woodmont Avenue. Woodmont Avenue, which becomes a southbound one-way street at the intersection, leads to Montgomery Lane, which provides access to MD 355 and eastbound MD 410 (Montgomery Avenue). MD 187 heads northwest from Woodmont Avenue as a four-lane highway with a
center left-turn lane that passes through a five-way intersection with the eastern terminus of
MD 188 (Wilson Lane), Arlington Road, and St. Elmo Avenue and leaves downtown Bethesda. The state highway veers north and becomes a six-lane divided highway north of Huntington Parkway at
Suburban Hospital, which sits opposite the southern end of the
National Institutes of Health campus. MD 187 intersects several entrances to the federal campus and passes to the east of the tiny village of
Oakmont at its junction with Cedar Lane. MD 187 enters Rockville at its
diamond interchange with I-495 (Capital Beltway). The state highway intersects Democracy Boulevard, a county highway that heads west past
Walter Johnson High School and the
Westfield Montgomery shopping mall. North of Democracy Boulevard, MD 187 meets I-270 (Eisenhower Memorial Highway) at an extended diamond interchange whose ramps also connect with Rockledge Boulevard. The highway intersects Tuckerman Lane north of I-270 and continues northeast toward the White Flint area of Rockville. At its intersection with Executive Boulevard, MD 187 reaches its northern terminus, with Old Georgetown Road curving to the east as a county road and heading toward an intersection with MD 355 (Rockville Pike) just north of the
North Bethesda station along Washington Metro's Red Line. MD 187 is a part of the
National Highway System as a principal arterial for its entire length. ==Bicycle infrastructure==