"Survivor registry" is a term coined in the wake of the September 11, 2001 attacks to denote web sites where citizens of affected cities could post a message saying they were okay. The attacks disrupted telephone communications, particularly in New York City, and for many people these sites became the best option for trying to get word of their safety to concerned loved ones.
What was probably the first survivor registry was created by computer programmer and science fiction writer William Shunn in Queens. At about 11:30 a.m. on September 11, in response to a friend's emailed suggestion that he maintain and circulate a list of acquaintances he had heard from thus far, Shunn posted the names of people he knew were okay on his personal web site and began sending the URL to other friends. Keeping the list up-to-date proved difficult, as more emails flooded in than he could handle. He quickly developed a simple database and form submission system so that visitors to the site could post their own names to the list. This automated system debuted at around 1:00 p.m. that afternoon.
Meanwhile, a crew of programmers at the University of California, Berkeley with vastly superior resources were working on a similar concept. Their survivor registry went online at about 3:00 p.m. Eastern time. While Shunn's site foundered and eventually crashed under the heavy load of submissions, the Berkeley site ran on a huge computer cluster, and for the next several days stood out as the most robust and accurate of the many survivor registries that followed.
One problem that plagued the survivor registries was that of inaccurate information. So many entries listed actual victims as being okay that Berkeley eventually implemented a system that used cross-checks to gauge the accuracy of the information received.
The grassroots generation of survivor registries led many people to wonder why the Federal government did not have such a system already in place. FEMA has since bruited about plans for official survivor registries in the future.