Maryland Route 190 (MD 190) is a state highway in the U.S. state of Maryland. Known as River Road, the highway runs from MD 112 near Seneca east to Western Avenue at the District of Columbia boundary in Bethesda. MD 190 parallels the Potomac River through the affluent southwestern Montgomery County communities of Potomac and Bethesda and connects those suburbs with Interstate 495 (I-495). River Road was paved from Washington west through part of Bethesda in the early 1910s. A second section of MD 190 was constructed through Potomac in the mid-1920s. The Bethesda and Potomac portions of the route were unified in the late 1920s. MD 190 was extended west toward Seneca in two steps in 1950 and the early 1970s. The highway was expanded to a four-lane divided highway through Bethesda in the early 1960s.