Born in St. Louis in 1843., Mayor Ewing was a great-grandson of Pierre Chouteau. His father headed a prosperous wholesale grocery business for many years. Upon graduation from Christian Brothers College, he become a clerk in his father´s business. The firm was dissolved following the elder Ewing´s death in 1873. Young Mr. Ewing became prominent in banking circles and also had farming and investment interests. In 1880 he married Miss Mary Flemming of Indianapolis, IN. They had one son, William.

In 1877 he was elected to the House of Delegates under the Charter and Scheme of Separation of 1876. He was made presiding officer of the House. In 1881 the City´s Republican Party Convention nominated him for the office of mayor. In the April election he defeated Mayor Henry Overstolz by 14,000 votes.

At the City election of April 1885, Mayor Ewing was defeated for reelection by David R. Francis. He assisted in the organization of the State National Bank in 1885 and was a member of its board of directors. In later years he supervised his farm near Vincennes, IN. He died there on June 4, 1905.