Just when I thought that there wasn't anything new to learn, I came across a group of poster stamps from this society.
Not only was I surprised that a group of people apparently regularly met to talk about covered bridges, but they have their own website:
http://www.tbcbspa.com/So naturally I had to buy the set of stamps:

Being in Los Angeles, covered bridges are no more "special" than railroad crossing signs.
Forgive my ignorance, but are covered bridges a "thing" in Pennsylvania?
Thanks,
Jim