1947.When did the Illinois Central first use the slogan "Main Line of Mid-America?"
That IS a bit subjective. But by 1955 it was basically everywhere on steel cars.Was there ever a point in time pre-ICG that the slogan could be said to be in widespread use?
Nope. The slogan was added to all STEEL cars, including the prewar ones.Was its use restricted to new cars purchased and built after the slogan's introduction?
Yes, if they were all-steel. And they didn't have to be rebuilt to get repainted. Back in the good old days railroads were still concerned about public image, and had money to repaint cars. Like I said above, by 1955 the slogan was everywhere, so it only took the IC about seven years to repaint their entire freight car fleet (which was something like the 10th largest in North America).Were older cars repainted with the slogan when rebuilt?
No. By 1947 all of the double sheathed boxcars had dropped off the IC roster (most were actually gone by 1940). And I don't have any photo evidence of ANY wood IC freight car getting the new slogan (that includes boxcars, gons, reefers and hoppers).Was the slogan ever applied to double-sheathed wood cars or single-sheathed cars?
Hope this helps!