Interestingly all photos I have seen show Christmas Trees stacked on flatcars with stakes made from long wood poles complete with bark. Of course these photos date from the 20's and 30's. The trees appear to be tied with twine, in bundles. Then the bundles are laid on their side on the flatcar.
Perhaps boxcars were used for those trees going further distances.
As for shipping dates, think more the end of Oct through Nov. Even for those whose tradition was to put the tree on Dec 24, the tree was still cut down at the tree farm in the northern US or Canada in Oct or early Nov. Shipping time along could kill weeks. As a child in the early 60's I remember the stores and tree lots were all filled with trees by Thanksgiving.
