Michael Clark emigrated to the United States at the end of the American Revolutionary War to avoid anti-Catholic persecution in England.

Edward Clark's father, James, was one of Michael's three sons, and was an architect in Philadelphia and a well-known teacher of architectural drawing.

Edward Clark's mother, Mary, was the daughter of John Cottman, a captain in the Pennsylvania Regiment during the American Revolution.

[1] During the American Civil War, Clark also designed and oversaw the construction of numerous arsenals, forts, and hospitals in the Washington, D.C., area.

[2] Clark was appointed Capitol architect by President Andrew Johnson upon his mentor's resignation on August 30, 1865, and completed the extension project in 1868.

[citation needed] Clark introduced many technological improvements to the Capitol, including electricity, steam heat, and elevators.

[citation needed] Also during Clark's administration, the Library of Congress moved to its own building, and the west central interior of the Capitol was reconstructed.