North Adams Delegate May 20-21,1919 pin

A pin/clip. I think it is made of brass, has tarnish spots in green. On the front is North Adams Delegate May 20-21, 1919. On the left side, inside a circle, is what looks like a train coming out of a tunnel or bridge. On the right side, inside a circle, is the state emblem of Massachusetts. I could not find any information about why, at the aforementioned dates and place, this pin was issued. Any information would be greatly appreciated, Thanks in advance, Reliving my youth