Dr Julie Rugg, from the Cemetery Research Group at the University of York, says the only solution to the crisis is to return to the "old tradition" of reusing graves.
Learning about strangers is part of what drives Cristina Lugo of New York, who with a club she calls the "Cemetery Girls" takes self-guided day trips to graveyards in the area.
Among the honors he wore publicly, including in ceremonies at Arlington National Cemetery, were the Marine Corps Combat Action Ribbon, the Navy Occupation Service Medal and the New York State Conspicuous Service Cross.