Nothing lasts forever. Not places or people, and especially not buildings. Even those buildings that were marked years ago for preservation can face marked changes or outright elimination. We who care most about the link our modern day and future community has to its past recognize that fighting the change time brings is fighting the ocean tide: there needs to be a strong will and a hardy effort to keep the water from eroding the land underneath us.

Take the National Register of Historic Places. According to a report by Adrienne LeFrance of Digital First Media, buildings or sites that were once deemed worthy of inclusion in the list have over time been removed. That does not de facto put them on the endangered list, but it does open the question up.

One of the persistent misconceptions about the list is that once a site is designated historic, it will remain forever protected and unchanged. Not so. States can request that a site be removed from the National Register of Historic Places at any time, and for any number of reasons, the report states. National Park Service records obtained and analyzed by Digital First Media show that states have requested the removal from the register of at least 1,752 previously designated sites since 1970. That's 2 percent of the total number of listed sites. In the past decade, there have been about 51 removals from the list per year, with occasional spikes. In 1999, for example, 138 sites were delisted.

“I believe that there is a correlation between tax credits and the number of new listings,” said Jeff Joeckel, an archivist for the National Register of Historic Places. “But I am not aware of any correlation between a strong economy and the number of removals.” Joeckel surmises that the 1999 spike may have come because states were overhauling computer systems ahead of the year 2000 as a way to prepare for potentially widespread computer problems that year, and happened to notice sites that needed delisting along the way.

Joeckel says he and most others in the preservation field are able to focus on the positives, despite the inevitable crumbling that comes with the passage of time. “But as the archivist,” he said, “you do look at the number of removed files and you're just wondering, ‘Aren't all of these that are listed eventually going to be over here?'”