When John King Longmire was born on 6 April 1870, in Blyth, South Australia, Australia, his father, Henry Longmire, was 34 and his mother, Ellen Martha Frost, was 34. He married Alice Fuller on 1 October 1893, in Undalya, South Australia, Australia. They were the parents of at least 2 daughters. He died on 25 March 1956, in Condowie, South Australia, Australia, at the age of 85, and was buried in Condowie, South Australia, Australia.