Before WCCO, there was the "Call of the North Station WLAG", a forerunner of WCCO. This is likely the earliest recording of a radio station in the Twin Cities and it is something called the National Defense Day Program in September of 1924. This broadcast took place about a month before WCCO went on the air October 2nd and is certainly one of the 100 moments in 100 years of 'CCO!
(Image: The original WLAG studio in the Oak Grove Hotel in downtown Minneapolis in 1924 where Chief Engineer Ray Sweet worked the phone.)