When Percy Beach McCoy II was born on 11 December 1889, in Brooklyn, Kings, New York, United States, his father, Walter Irving McCoy I, was 30 and his mother, Kate Philbrick Baldwin, was 28. He married Marguerite Louise Maury on 12 June 1929, in Chevy Chase, Montgomery, Maryland, United States. They were the parents of at least 2 sons. He lived in Arlington, Virginia, United States in 1940 and Alexandria, Fairfax, Virginia, United States in 1962. He died on 28 April 1963, in Caldwell, Essex, New Jersey, United States, at the age of 73, and was buried in Arlington, Virginia, United States.