[1] At 19, McEwen married Isobel Taylor and, following the birth of their first child, emigrated to Canada in May 1912 where he began his career as a blacksmith in Moren, Manitoba.
The family moved to Winnipeg the next year where McEwen joined the Blacksmiths and Horseshoers union and then to Swift Current, Saskatchewan in 1914.
McEwen was branch secretary and leader until 1927 when he moved to Winnipeg to work full-time as the party's organizer for Manitoba and Saskatchewan.
In 1935, McEwen was a lead organizer of the On-to-Ottawa Trek of unemployed people which was violently broken up in Regina, Saskatchewan.
The eight, including Communist Party leader Tim Buck were sentenced to five years in Kingston Penitentiary for being members of an organization declared illegal under Section 98 of the Criminal Code.
[3] Subsequently, McEwen moved to Vancouver, British Columbia where he was appointed editor of the party's west coast newspaper, the Pacific Tribune, which he edited until his retirement in 1970.