When Robert Clark Sweezer was born on 18 June 1889, in Boone, Missouri, United States, his father, James Marion Sweezer, was 27 and his mother, Mary Ellen Brooks, was 21. He married Letha Ester Fenton on 20 July 1908, in Fayette, Howard, Missouri, United States. They were the parents of at least 6 sons and 1 daughter. He lived in Rocky Fork Township, Boone, Missouri, United States in 1920 and Marceline, Linn, Missouri, United States in 1930. He died on 9 January 1974, in Centralia, Boone, Missouri, United States, at the age of 84, and was buried in Marceline, Linn, Missouri, United States.