These miniatures depicting the futuristic world of NYC in 1980 appeared in the January, 1931 ish of Modern Mechanix, as part of a feature on the burgeoning art of special effects miniatures for motion pictures:
This model took five months to complete and cost approximately $200,000. It was built in an old blimp hangar once used by the U. S. Army balloon corps and covers a ground area 75×225 feet, representing the most extravagant effort yet conceived by the American cinema industry.Link
Lofty office buildings 250 stories high, canals carried overhead on suspension cables, airplanes that land on a few square feet of flat space on the side of tall structures, streets with nine lanes and nine levels of traffic, are among the interesting features. Although the model city is futuristic, its construction violates no engineering practices. It is really engineering skill carried a bit farther than today.