Thanks to Modern Mechanix we can now see what New York was supposed to look like by the year 2000, as seen from 1927. In that article "streets on five levels have been prophesied," but by 1931, two-level streets (pictured) seemed more realistic.

A definite step towards the relief of traffic congestion on much traveled city thoroughfares by the construction of streets under streets is soon to be taken by the city of New York. When this stupendous project has been brought to completion the metropolis will have an underground lane for fast through traffic, a tunnel for local and express trains, all built underneath the surface street, which will be left for local traffic. more ›