During its heyday, the depot hosted the passenger trains of nine railroads, and more than 20 million pieces of mail passed through the station to the neighboring St. Paul Central Downtown Post Office annually. At its peak in the 1920s, there were 282 train movements daily. The waiting room stood atop nine platforms serving 18 tracks; the eight northern ones closest to the headhouse were stub-end tracks, while the other ten ran through. However, track ownership and trackage rights west of the station meant that most trains operated as though the station was a stub terminal. These trains, when they were intended to continue beyond the station, instead backed up to a wye just to the east to get to other main lines.