I didn't know about it, but further reading revealed that this cemetery is apparently a kind of "potter's field" where the poor and unidentified were buried in mass graves for years.
Over a million people are buried in the citys potters field on Hart Island. A New York Times investigation uncovers some of their stories and the failings of the system that put them there.
Twice a week or so, loaded with bodies boxed in pine, a New York City morgue truck passes through a tall chain-link gate and onto a ferry that has no paying passengers. Its destination is Hart Island, an uninhabited strip of land off the coast of the Bronx in Long Island Sound, where overgrown 19th-century ruins give way to mass graves gouged out by bulldozers and the only pallbearers are jail inmates paid 50 cents an hour.
There, divergent life stories come to the same anonymous end.
No tombstones name the dead in the 101-acre potters field that holds Leola Dickerson, who worked as one familys housekeeper for 50 years, beloved by three generations for her fried chicken and her kindness. She buried her husband as he had wished, in a family plot back in Alabama. But when she died at 88 in a New York hospital in 2008, she was the ward of a court-appointed guardian who let her house go into foreclosure and her body go unclaimed at the morgue.
https://www.nytimes.com/interactive/2016/05/15/nyregion/new-york-mass-graves-hart-island.html