When Mildred May Thatcher was born on 19 February 1888, in Williamsburg, Hampshire, Massachusetts, United States, her father, Alvin Ruiz Thatcher, was 32 and her mother, Mary Anna Connell, was 27. She married John Worcester Light on 28 November 1917, in Lebanon, Pennsylvania, United States. She lived in Mercer, New Jersey, United States in 1910 and Washington, District of Columbia, United States in 1930. She died on 11 December 1947, in Takoma Park, Montgomery, Maryland, United States, at the age of 59, and was buried in Arlington National Cemetery, Arlington, Virginia, United States.