Chicago World's Fair 1933-4 was the major jumping off point for model trains ...with millions viewing the large commercial O scale layouts.
1934 Lionel displays thier City of Portland streamliner along side the Union Pacific prototype and Lee B Green has a display of his TruScale Mi-Loco 17/64ths scale O gauge trains.
Mi-Loco offered easy to build kits or RTR models at much lower prices than custom builders . Mi-Loco pieces were 17/64th scale which is the "true scale " for O gauge track .
Please see photos comparing Mi-Loco Hudson next to 1/4 scale Icken .
Also compare sand cast Mi-Loco next to die-cast Mini-Scale ..after Green lost his company to Congress Tool and Die.
To see video of train running please see link