I once got a tour of a cemetery, and as  he manager showed me around, he  pointed out several monuments of noteworthy people of the community, giving a brief history of individuals lives etc. I pointed to an unmarked section and asked him if that was for future development. He told me there were already thousands of burials already there, all unmarked, from the Spanish Flue epidemic of years ago. People were dieing   faster than they could be individually buried, so they were simply  put in a mass grave. I asked about identification, and as I understand it, records were sketchy, some records were left, but not many. I have that picture in my minds eye to this day. I feel the same way about this post. With advancement in technology, hopefully identification of all can be made, and relatives notified.

For decades, the stretch of grassy land in an elbow of the Mississippi River held no trace of the people buried underneath.

No signs, markers or tombstones pointed to the more than 300 African-American former slaves buried in two cemeteries about 20 miles west of New Orleans. Only a handful of people knew they ever existed, despite their being listed on the National Register of Historic Places.

via Efforts mount to locate, preserve sites in many locations – USATODAY.com.