From 1906 to 1910, MacDonald worked as a clerk and stenographer in office of governors Curtis Guild Jr. and Eben Sumner Draper.

He later resigned to serve as recorder of the Massachusetts Land Court, but on January 1, 1925, he became secretary to governor Alvan T.

[1] In 1928, former registrar of motor vehicles Frank A. Goodwin alleged that MacDonald ran the state while Governor Fuller was absent, which was "pretty much of all the time during the past four years".

[7] At the party convention, MacDonald finished in last place on the first ballot with 84 votes to Oscar M. Dionne's 279, Samuel H. Wragg's 170, and Richard E. Johnston's 99, and withdrew his candidacy.

[10] He was removed from the position in 1946 by Governor Maurice J. Tobin on the grounds that he had inefficiently managed the Federally-funded roads program.

During World War I he served as a field artillery captain with the 26th Infantry "Yankee" Division in France.