The route of the layout lies somewhere between mileposts 206.1 and 230.0, roughly between Chambers and Adamana Arizona. Below you can take a look at rail lines throughout Arizona in the 1950's and the milepost points in the area that the layout covers.

Arizona rail lines in the 1950's.	Milepost and Number map of the line.

 

As the image below shows, the grade westward between Pinta and Adamana steadily levels down, eventually becoming level at the Winslow Yard.

Elevation map between Winslow and Pinta.

In real life Route 66 doesn't come quite as close or in orientation as it does on the layout, below you can take a look at how it really is.