He served as a member of the Maryland House of Delegates, representing Cecil County from 1894 to 1896 and from 1900 to 1901.
[3] Mackie attended Cecil County schools and graduated from the University of Pennsylvania.
[4] In 1908, Governor Austin Lane Crothers appointed Mackie as state veterinarian.
[1][7] Mackie ran for the Democratic nomination for the Maryland Senate in 1930, but lost to Cecil Clyde Squier.
[5][2] Mackie died on May 18, 1939, at the age of 74 or 75, at his "Turkey Point" farm, near North East.