Did men really wear suits, ties, dress shoes and hats to the fair?
Did women really wear high heels?
I know folks dressed up much more than is the norm now, but I can't imagine that they dressed up so much for the fair.
Man is the Only Animal that Blushes. Or needs to.
Mark Twain
It looked kinda odd especially with the guys in the suits and ties. What I recall from photos from the era was that people dressed up to go to public events. Look at photos from sporting events of that time -- coats, ties and hats.
I think status had a lot to do with it. People showed they had money enough to be able to afford and wear nice clothes. For a state fair it showed they were successful farmers not farm hands. You didn't have to wear the kinda clothes you wore for work for social occasions
Somewhere in the 60's that changed. Jobs shifted from agriculture and industry to "white collar" jobs. Work clothes were suits and ties. Your had to wear them. Of course if you are affluent enough nobody tells you what you have to wear. Casual then became the way to dress in public, it said -- I can dress the way I want. Plus it was more comfortable.