Christmas 2012 - - An extended view of the Trump buildings which have been placed on top of the old rail yards which used to cover the upper west side.
You can just see the remains of the last "float bridge" which was used to load rail cars (freight not passengers) onto barges to move them around the harbor.
In olden days, Vanderbilt decided that passenger traffic would come down the East Side and freight on the West Side, so the division between the "sides" was born. Just a commercial decision by the NY Central Railroad.