He served as the United States Permanent Representative to NATO (an ambassadorial-level appointment) between 1969 and 1971.

In 1945, he was graduated with a baccalaureate in engineering from the University of Kansas, where he had been a member of the Alpha Nu chapter of the Beta Theta Pi collegiate fraternity.

[4] While serving as a congressman for Kansas's 1st congressional district, Ellsworth voted present for the 24th Amendment to the U.S.

[7] On November 9, 2010, Ellsworth provided commentary to KFMB regarding an unexplained vapor trail in the airspace off the coast of Los Angeles which, at the time, was widely speculated to be a missile launch.

"[8] Ellsworth died in Encinitas, California: near the small city of Solana Beach, where he had founded and directed a research firm, Hamilton BioVentures.