I collect all sorts of pins, buttons, pinbacks, etc, mostly from Minnesota celebrations including Defeat of Jesse James Days, Bullhead Days, the St Paul Winter Carnival and the Minneapolis Aquatennial.  The Aquatennial started in 1940 and has had solid annual celebrations accept the 1945 and 1946 during the war.  As I write this, there are 66 pin years available and I have 60 of them. 

These are very interesting to view.  I especially love the re-occurring skipper wheel theme.