The AP has an extended piece on the Doe Network, whose mission since its inception in 2001 is to highlight missing and unidentified persons and do their best to resolve such cases:
Today the Doe Network has volunteers and chapters in every state. Bank managers and waitresses, factory workers and farmers, computer technicians and grandmothers, all believing that with enough time and effort, modern technology can solve the mysteries of the missing dead.
Increasingly, they are succeeding.
The unnamed dead are everywhere -- buried in unmarked graves, tagged in county morgues, dumped in rivers and under bridges, interred in potter's fields and all manner of makeshift tombs. There are more than 40,000 unnamed bodies in the U.S., according to national law enforcement reports, and about 100,000 people formally listed as missing.
The premise of the Doe Network is simple. If the correct information -- dental records, DNA, police reports, photographs -- is properly entered into the right databases, many of the unidentified can be matched with the missing. Law enforcement agencies and medical examiners offices simply don't have the time or manpower. Using the Internet and other tools, volunteers can do the job.
40,000. That is a ridiculously large number that has no business being so high. The Doe Network does its part, and eventually the linking of both databases in the National Missing and Unidentified Persons System (NamUS) should as well, but still. Think about that number. Think long and hard.