Because of all the craziness going on, as of 6/19/20 one of the monuments has been move inside of a private club to prevent any vandalism.
There in now a plaque with the needed date.
Almost every day we drive by hidden monuments, memorials’ and plaques, some we see but most we don’t 
This will take you on a driving tour of some that are in our town. It should take about 1 hour. You will need a Wherigo player and down load the cartridge here http://www.wherigo.com/cartridge/details.aspx?CGUID=7fa1c759-10d4-4949-a9db-0de91901ff42