Awesome, thanks for the info! I hadn't heard of the park or the dock being used for passenger service.
Here is a picture I dug up at the U of M historical library, believe it was taken in 1929 or 1920, shortly before it was retired. The warehouse that was extended out onto the dock from the original freight house is visible behind the last boxcar:
The low level of Lake Michigan exposed the "ruins" seven years ago or so:
The area immediately east of the dock was noted as "city dumping grounds" on a Sanborn map from the 20s or 30s, which would at least partly explain how the waterfront crept outward there.