[5] He graduated from Hamline University in St. Paul, Minnesota, where he was active in drama, president of his fraternity, and captain of the tennis team.

[6] Sundberg left teaching English literature for acting, appearing in plays in stock theater in New England.

[5] His most notable roles were Mr. Kraler in the original 1957 production of The Diary of Anne Frank and Mortimer Brewster (as a replacement) in the 1944 Arsenic and Old Lace.

He played Mike, the bartender who listens to Judy Garland's character's troubles in Easter Parade.

In 1962, he played the lead guest-starring role of Luther Boardman, a naive but troublesome newspaper publisher who comes to Laramie, Wyoming in "The Man Behind the News", one of the last episodes of the western series Lawman.