After a brief stint in professional baseball, playing for the Portland Beavers, McCallum moved to New York City, where he began his sportswriting career.
[1] In 1961, he married television and movie actress Marjie Millar having met her while writing a book about her but the marriage lasted only a few years.
McCallum's student activities included being a member of the WSU Cougar varsity baseball team, coached by Buck Bailey.
He moved to New York City in 1947 and eventually served as assistant sports editor of the Newspaper Enterprise Association from 1950 to 1954.
One of his most famous works is The Tiger Wore Spikes, a biography of baseball Hall of Famer Ty Cobb.