Railway Exchange Building(s) - Trains Magazine

I happened upon a commercial building located in downtown St Louis called "The Railway Exchange Building".

Curious because of the name, I tried to do a little research into the origination background of the building, to learn that there were identically named buildings in Chicago, Milwaukee, Muskogee, and Portland.

Unfortunately while there is a wealth of information available on efforts to redevelop and repurpose these buildings, very little information seems to be available tying these buildings to rail related trade, their original developers, or what functions the buildings served.

Anybody have any specifics?  It's easy to imagine these buildings being the "Trailer-Trains" of railroad corporate offices, but having nothing more than intuition to go upon, is frustrating. Anyone have specific knowledge they would care to share?

Were these buildings built by the railroads for their own use, or did independent developers build these buildings  in expectation that having all the railroads under one roof would be a good selling point to lease space?

Was there any kind of open brokerage where "connections" were made through competitive bidding processes, or were more relationships of the "good ol boy" type where you just naturally went to one particular railroad to link into specific geographical areas?