McNary served as member of the City of Boston Common Council in 1887 and 1888. McNary served in the
Massachusetts House of Representatives from 1889 to 1890 and the
Massachusetts Senate from 1891 to 1892. As State Senator, McNary served as an alternative delegate to the
1892 Democratic National Convention. In 1893,
Robert Grant resigned his position on the Boston Water Board and McNary was appointed to fill the vacancy in July. He served until 1894.
Failed congressional runs In 1892, McNary secured the Democratic nomination for
Massachusetts's 10th congressional district, centered on the heavily Irish Catholic industrial neighborhoods of South Boston, Roxbury, and Dorchester. The district was one of the most Democratic in the overwhelmingly Republican state. However, State Senator
Michael McEttrick, running as an independent Democrat, won the race in a three-way contest against McNary and Republican
Harrison Atwood.
Return to state politics In 1898, McNary was elected secretary of the Massachusetts Democratic State Committee. In 1900, McNary returned to the Massachusetts House of Representatives and was elected Chairman of the
Massachusetts Democratic Party. McNary was elected a delegate to the
1900 and
1904 Conventions. == U.S. Representative ==