For your consideration, here is a 1990 Metro Transit Grand Opening Pinback Button, Pin, for the Seattle Convention Place Station, from Washington, dated September, 14th, 1990.  It has a little wear on it and a little tarnish on the back.  The button has a diameter of 1 5/8 inches.  Item pictured is the actual item up for sale and comes from a non-smoking household.  (542.754y-.4px2)