This is the Circus World Museum in Baraboo, WI. The photo was taken in 1968. Notice the BLUE railcar behind the Merry-Go-Round. This was a Baggage car that the Museum utilized for a lot of exhibits on the inside where the customers could walk thru the car.
According to the work that Fred Dahlinger Jr. did while he was employed at the Museum, this car was built by the Barney and Smith Co. in 1911. It served on the Milwaukee Railroad as car # 1025. It was gifted to the Museum by the CMStP&P Railroad in 1964. ( Can someone help with those initials? )
Somewhere along the line it was repainted Yellow. It was last used in the 1980's as an exhibit car.