When Kenneth Mc Millan Ellsworth was born in March 1907, in Rigby, Jefferson, Idaho, United States, his father, Seth Millington Ellsworth, was 36 and his mother, Margaret Mckay McMillan, was 41. He married Josephine Allen on 6 May 1930. They were the parents of at least 1 daughter. He lived in Idaho Falls, Bingham, Idaho, United States in 1910 and Lewisville, Jefferson, Idaho, United States in 1920. He died on 21 February 1991, in Sacramento, Sacramento, California, United States, at the age of 83, and was buried in Sacramento, Sacramento, California, United States.