Taggart, an Irish-born immigrant, came to the United States in 1861 at the age of five, grew up in Xenia, Ohio, and moved to Indiana as a teenager. After relocating to Indianapolis in 1877, he began a successful career as an hotelier, financier, and politician. As the party's county chairman during Grover Cleveland's 1888 presidential campaign, Taggart helped him carry Marion County over Republican Benjamin Harrison, the hometown candidate. As state chairman in 1892, Taggart helped Cleveland carry Indiana in opposition to Harrison's bid for reelection. In 1908 Taggart assisted in securing the Democratic nomination of John W. Kern for U.S. vice president and Thomas R. Marshall for governor of Indiana. He was also involved in securing the nomination of Woodrow Wilson for U.S. president and Marshall for vice president in 1912, as well as James M. Cox's nomination in the 1920 presidential election. In addition to his political activities, Taggart was the owner and developer of the French Lick Springs Hotel in Orange County, Indiana; he also maintained a summer home at Hyannis Port, Massachusetts.