It's ages since I visited this site. I hope that you will nevertheless treat my request with the civility, erudition and consideration that I remember. It's a request about a song, though not about "folk and roots" music.

George Gershwin's song, They All Laughed, begins
The odds were a hundred to one against me
The world thought the heights were too high to climb
But people from Missouri never incensed me
Oh, I wasn't a bit concerned
For from hist'ry I had learned
How many, many times the worm had turned...

My question is this: what is the significance of "people from Missouri never incensed me?"

Are Missourians renowned for provoking anger in those who come into contact with them, or what?

Thanks in anticipation.