Harold Rasmusson was born in Minnesota. He studied at the Minneapolis Art School and began his career as a fashion illustrator. He eventually settled in New York City, where he took on drawing comics in 1946. He is the creator of 'Aggie Mack', a comic strip about a young girl that was distributed by the Chicago Tribune New York News Syndicate and ran until the artist's death in 1961. Until 1953, Rasmusson also made the accompanying strip 'Honey Bun'.
'Aggie' became especially popular in France, where it first appeared in Fillette in 1947, and was continued in a European version drawn by Gérard Alexandre, who signed with the pseudonym Al.G. In America, the series was taken over by Roy Fox in 1962.