Air Rights

The Merchandise Mart was Chicago's second air rights project. The concept of air rights today, which includes unused, zoned air space above a building, differs from the concept in the 1920s, which pertained solely to air space above railroad tracks and facilities. Air rights were defined in 1927 by Joshua D'Esposito, the consulting engineer for the Daily News Building, as "the space above a plane of clearance over railroad tracks and facilities, capable of utilization for the construction of streets and buildings in the same manner as if the railroad facilities did not exist."

On November 23, 1927, The Illinois Commerce Commission granted Marshall Field's request and approved The Merchandise Mart project to proceed.

In Chicago, the immensity of early buildings and complexes built on air rights, and the fact that the railroads were all located along the Chicago River and Lake Michigan, presented challenges to developers and architects to ensure that the large scale projects did not isolate the buildings from the urban context or isolate the public from the benefits of the waterfront.

The air rights agreement between Field and the Chicago and North Western Railroad included Field purchasing the railroad's air space above the 458 small parcels of land (each had a separate deed) in which to sink the caissons for supports, plus a number of linear strip lots on the site necessary for the building's elevator shafts, machinery room and sundry mechanical requirements. The railroad, which had not used the Wells Street Depot for passenger service since 1911, would build an entirely new station at ground level on its remaining property within the new building to be connected by elevators to the Chicago Tunnel Company's lines under the site. Because the new station would not be seen or used by the public, Graham, Anderson, Probst and White's design was not compelled to indicate the railroad's facilities or provide for the pedestrian's needs in the elevation of the building. The architects' approach to site planning was predetermined by Simpson's intention to create the North Bank Drive to correspond to the recently completed Wacker Drive.