Clarke graduated from Cornell University in 1913; a civil engineer and landscape architect, he returned to Cornell in 1935 as a professor of city and regional planning, and subsequently become Dean of the College of Architecture. Also in 1935, he and Michael Rapuano established their architectural practice, specializing city planing and landscape architecture. Clarke was president of the firm from 1962 until his retirement in 1972.
From 1923 to 1933, Clarke served as landscape architect to the Westchester County (New York) Park Commission, and in 1933, became a consultant to the New York Department of Parks, under Robert Moses. In these positions he was associated with the creation of the Saw Mill, Henry Hudson, Hutchison, and Taconic parkways, and the Whitestone and Triborough bridges, as well as renovations of Bryant and Central Parks. He was also a member of the board of design of the 1939 New York World's Fair, and in the late 1940s and 1950s was among the architectural consultants involved in development of the United Nations headquarters complex on New York's East Side.
Clarke was also highly influential in design decisions in the nation's capital as chairman of the Washington, D. C. Fine Arts Commission from 1937 to 1950, during which time he was responsible for locating the Pentagon building in Arlington, Virginia, away from historic sites. He was dismissed from the chairmanship by President Harry S. Truman in a highly publicized disagreement over the addition of a balcony to the west facade of the White House.
Clarke was a trustee of the American Academy in Rome, and of the American Museum of Natural History in New York. He was the Academy's assistant corresponding secretary from 1950 to 1956, and was returned to the Council for three-year terms in 1960 and in 1964. He was on a cruise and off the coast of Denmark at the time of his death.
