In Vonnegut: pg 390 "He said that after the war he was going to have a regimental reunion in his home town, which was Cody, Wyoming."
Wikipedia states: "Cody is a city in Park Country, Wyoming. It is named after William Frederick Cody, primarily known as Buffalo Bill. The population is 9250."
It is very close to Yellowstone Park.

Cody Wyoming was mentioned in the text when the colonel was dying, he said that when the war was over he was going to have a reunion in his home town- Cody.