I was curious how long the average geocache lasts, so I did a little research.
I examined all of my finds (from GSAK) that have been archived, excluding events, CITOs and other event-type caches. The chart shows the median number of days between placement of the cache and the final log, which was normally the archive log.
I have a theory, several of them in fact, to account for the results. First of all, I think 2001 is a special case. Caches placed back in the very early days achieved a sort of iconic status and have been kept alive by others long after the original owner has left the geocaching world. This is true for the two year 2000 hides I found, both of which are still active. It is also true for many year 2001 caches that are still active, but not shown on the chart. I checked about half of my 2001 archived caches on the chart and three of those had been adopted during their lifetime. The same did not appear to be true (or as true) for the 2002 caches.
For 2002 and 2003, I believe the short duration was due to the learning curve of the flood of new cachers entering the sport. I know my early hides were not well-chosen spots. After a few that were lost to gardeners, thieving muggles, or construction crews I learned what kind of spots worked better. The period 2004 through 2008 shows pretty good consistency, with a median lifespan of about 2200 days (a little over six years). Remember, these are median lifespans. Half of the archived caches lived longer than that, and of course many are still active. For those years after 2008, the apparent shorter lifespan, I believe, is explained by the fact that longer-lasting caches are cut off by the simple fact that it hasn’t been long enough since those were hidden for them to live out a normal span. Put another way, one end of the bell curve of longevity (caches that last 8 years or more) is cut off by insufficient passage of time, causing the median age to be lower. I suspect that if this same exercise were to be done in five years you’d see caches from 2008 to 2013 or so have the same median of around 2200 days.
There could be other explanations. Since these are my finds, maybe I cached differently in the years 2005 – 2008 from later years. Maybe the changing rules from Groundspeak have caused people to hide caches differently. Feel free to posit your own theories in the comments.