I have to disagree it is quit possible. There is an API method to get the oldest caches from an area. I have a checker that can do it see for example this tag
http://project-gc.com/Challenges/GC2X4ZR/10411 there is an API metod to get the oldest cache in an area called GetOldestCaches
There exist an checker that checks that you have found the oldest caches in a number of states in north america that I have helped to code.
Unfortenally I cant find it right now. But remembered the problem with it was that it is slow to get the oldest caches.
A real problem might be what is the oldest cache? the API metod only looks for the hidden date and sometime it is incorrect. For example thee oldest cache in Sweden is
GC1CWX1 ABEN 1991-09-16
GC4D Match Stash 2000-08-11
C602 Americana Cache 2001-04-03
The first one is published in 2008-07-03 and the hidden date is a part of the problem.
The secon one is hidden that date but was archived for a couple of years might have been missing I dont know
The last one has never been archived.
The cahe with the oldes hidden date is GC56D9R Schlawynski und das geheimnisvolle Buch hidden in 1900-05-12