Chuck, you are bringing up a great point, and one that worries me all the time. When I travel with my camera sometimes I think NAH, I WILL SHOOT IT NEXT TIME, and as you point out NEXT TIME might be too late.
Most of these old abandoned places are being demolished and lost forever, so we can all learn from your lesson.
IF YOU SEE IT, PHOTOGRAPH IT NOW. Don't wait. Next time it just might be too late.
All of these old buildings are either being replaces with nature (in rural places) or with fast food restaurants, banks, and strip malls. The landscape of this country has changed into one giant conglomeration of cheap, say-nothing bungalows.
And one day very soon nobody will know a darn thing about these buildings and/or cars. Everyone will live inside a drawer in polluted cities, eating bugs, etc . . .
Far fetched? Maybe, but these things are being erased as we speak.