There are three costs basically: - storage, which is pretty darn cheap, easy to predict, easy to budget for, etc.. - retrieval for FOIA, which is easily quant

There are three costs basically: - storage, which is pretty darn cheap, easy to predict, easy to budget for, etc.. - retrieval for FOIA, which is easily quantified in workhours and sometimes deferred via fees. - liability, which is very hard to quantify, considering you never know what skeleton a nosy citizen would be able to uncover. The latter is mainly the reason public records disappear. I'm glad most parts of the US are still in the 'let's take this to court' territory. We should be very afraid if we go into the 'an unfortunate accident destroyed all the records' area of dealing with this stuff.