I checked with my sister (2 years younger than me), and she corrected me to note we went from Chicago to Reedsburg, Wisconsin with my grandmother. It would have been a regular train, very probably a diesel engine. We went many years to visit my aunt and uncle (really my mother's cousins) on the farm for the summer. My dad must have driven us in the car the other years. Wikipedia says that service was via the Chicago and Northwestern, and ended in 1963.
https://en.wikipedia.org/wiki/Chicag...urg,_Wisconsin)