Massachusetts Avenue (Washington, D.C.)

Massachusetts Avenue is a major diagonal transverse road in Washington, D.C., and the Massachusetts Avenue Historic District is a historic district that includes part of it.

Massachusetts Avenue was part of Pierre Charles L'Enfant's original plan for the development of Washington, D.C. The avenue crosses three of Washington, D.C.'s four quadrants. It intersects every major north–south street and passes numerous Washington landmarks. Massachusetts Avenue represents the northern boundary of downtown and the city's Embassy Row.

Massachusetts Avenue is tied with Pennsylvania Avenue as the widest road in Washington, D.C., at 160 feet (49 m). The two roads run in parallel through much of the city, Massachusetts about seven blocks north of Pennsylvania Avenue. Massachusetts Avenue was long considered the city's premier residential street, and Pennsylvania Avenue was its most sought-after business address. The two avenues are named Massachusetts and Pennsylvania, two states that played a leading role in securing American independence in the American Revolution and the subsequent Revolutionary War.

The historic district is an 81-acre (33 ha) area in Northwest Washington, D.C. that includes 150 contributing buildings and three contributing structures. In 1985, Massachusetts Avenue was listed on the National Register of Historic Places. It includes multiple properties that are individually listed on the National Register.