When Oliver Hansen was born on 8 May 1851, in Ishøj, Copenhagen, Denmark, his father, Hans Hansen, was 39 and his mother, Bertha Marie 'Mary' Madsen, was 29. He married Sarah Wilson in 1881. They were the parents of at least 1 daughter. He lived in Ishøj, Smørum, Copenhagen, Denmark in 1855 and Kane Township, Pottawattamie, Iowa, United States for about 10 years. He died in September 1922, in Jackson, Missouri, United States, at the age of 71, and was buried in Independence, Jackson, Missouri, United States.