Stamps on Checks
Checks started being taxed in 1898 to pay for the Spanish-American War. Banks were supposed to apply revenue stamps to canceled checks. But most banks didn't understand the rule was to use revenue stamps, and not postage stamps, and it's common to find postage stamps on old checks of this era. Correct stamps will say “documentary” on them, and not “postage.” While this may not seem like a big deal, the US Post Office dept. got the revenue from postage stamps, while the Treasury only got the revenue if banks used revenue stamps, so the Treasury lost out. The tax didn't last that long.
We note the good folks in Monterey attached the proper stamps.