Reily was born in Sedalia, Missouri, but moved to Fort Worth, Texas, as a teenager, where he worked both in the newspaper and real estate businesses.

As a newspaper editor in Kansas City, Reily was said to be the first prominent figure to endorse Warren G. Harding for the office of President of the United States.

When Harding was elected president in 1920, he is said to have sought an appointive office to which he could nominate Reily as a reward for his loyalty without giving him too much power or presence in Washington.

Under pressure to leave office, and suffering from an illness he had contracted during a return visit to the continental United States, Reily resigned as governor on February 16, 1923.

He was succeeded by the U.S. Representative Horace Mann Towner, the Chairman of the House Committee on Insular Affairs, which had jurisdiction over Puerto Rico.