The CN boxcar is just one of the many interesting details visible in this photo. Jack Delano photo, Library of Congress, Sheldon Springs, Vt., September 1941.
In the steam era boxcars hauled virtually every commodity that didn't need to be temperature controlled. That included dimensional lumber and pulpwood.
The reporting marks on the car end are CN 511534, marking this as one of a large class (~1,700 cars) of Canadian National single sheathed boxcars.
Sylvan Scale Models and Steam Shack (F&C) both offered these cars as HO scale resin kits over the years. And Ted Culotta's Essential Freight Cars (Number 8, November 2003 RMC) gives additional details on these cars.