He clerked for two former judges after law school and entered into private practice in 1902. In 1905, he became the director of the Department of Public Health and Charities in the Weaver administration. He was active in the local Republican Party and won a seat in the lower house of the Philadelphia City Council, the Common Council. Mackey ran for the U.S. House of Representatives against DemocratJames Washington Logue and Frederick S. Drake of the Washington Party, but finished third. Later, he served as the director of the Department of Public Works and chairman of the Pennsylvania Workmen's Compensation Board. In 1925, he won election as the City Treasurer of Philadelphia. Mackey was close to Republican Party boss William Scott Vare and was his campaign manager in his 1926 campaign for the Senate. Vare defeated incumbent Senator George W. Pepper and Gifford Pinchot in the Republican primary and William Bauchop Wilson in the general election but was not seated by the Senate after a three-year inquiry into campaign spending and vote fraud. In 1927, Mackey ran in the 1927 Philadelphia mayoral election as the candidate of William Vare. His main opponent was J. Hampton Moore, a former mayor who ran under the banner of the Citizens Party. Mackey campaigned against the Kendrick administration charging corruption in the police force to the tune of hundreds of thousands monthly in illicit payoffs. On Election Day, Mackey defeated Moore by a large margin. Over time, his position on prohibition changed during his term. His chief supporter, Vare, was “wet”; however, after his election, Mackey declared himself as a “dry” who was in favor of prohibition. Part of his initial program would include going after payoffs from saloon keepers and speakeasies. In 1930, delivered a speech that denounced prohibition, which local observers attributed to the mayor throwing hit hat into the 1930 election for governor as a “wet” candidate. By 1929, Mackey was supporting a rival electoral slate to Vare, which led to conflict between the factions. Meanwhile, Vare's counsel Made references to having information about Mackey that could result in indictment or impeachment. After he left office at the end of 1931, Mackey entered the race for the United States House of Representatives, but was unsuccessful.
Personal life
He was married to Ida Mackey and had one daughter, Lorna. Mackey died in 1938 in Philadelphia from pneumonia. He had been bedridden for two months after an automobile accident.
