Nearly 600 unmarked graves have been discovered in Sandy Ground, Staten Island, which is one of the oldest communities in the United States that was founded by free slaves before the Civil War. Researchers conducted a special ground-penetrating radar search at Rossville A.M.E. Zion Church Cemetery and located the 576 graves—previously, the cemetery had only 97 known burial sites.

The search was commissioned by the New York Landmarks Conservancy and funded by an $18,000 grant from the Richmond County Savings Foundation, the Staten Island Advance reported.

"In a lot of early African-American burials, a lot of graves were never marked. It wasn't part of the tradition," Peg Breen, president of The New York Landmarks Conservancy, told the Advance. "Or the graves were marked with Yucca plants that you'll see here in the cemetery, or there were wooden shafts stuck into the ground, or bricks and plates on top of the graves. Wooden markers disintegrated, stones got displaced through the years, so even graves that were marked became unmarked through the years."

In 1828, a man named John Jackson, the first known free African-American in the local area, purchased land in Sandy Ground just after slavery was abolished in New York in 1827. Over the following years, the area was settled by African-American oystermen fleeing Maryland, where slavery wouldn't be abolished until 1864. Sandy Ground was the first free black community in New York, and was a social and political center for free blacks on the East Coast. By 1880, the community numbered 150, and by 1910, that number had grown to 200.

In the 1960s and 70s, however, the community was swept up in the suburban expansion that overtook Staten Island, and a fire in 1964 destroyed many buildings. Today, a small historical society in Rossville still exhibits letters, photographs, film, art, quilts, and books collected from homes in the area, and sees some 10,000 visitors a year.

The cemetery at the A.M.E. Zion Church, where these 500-plus graves were just discovered, is believed to be the only intact 18th-century African-American cemetery in the country. The church has stood since at least 1897, and was a stop on the Underground Railroad for escaped slaves.

Today, there are only 10 families remaining in the Rossville community whose ancestors were Sandy Ground settlers, according to the Advance.

The church is now hoping to identify some of the unmarked graves and mark the graves' locations. The cemetery will undergo repairs, and the church hopes it will become a stop on historical tours of Staten Island.

"It's kind of daunting and amazing and exciting all at the same time," Janet Jones, pastor of the church, told reporters yesterday. "We had no idea that there were that many gravesites out there."