Also,I-91 intersects with I-84,which heads toward New York City and Pennsylvania.
Let me explain the lumber sawmilling industry. All sawmills are specialized. The biggest production mills that make multiple railcar loads of lumber/day are spitting out 2x4, 2x6, 2x8 like crazy. They buy softwood species like Spruce back east. Out west they buy Spruce, Lodgepole pine, Hemlock, White fir and Douglas Fir. This is all construction lumber.
Also out west there are mills that pretty much only run Western red cedar.
There are also sawmills that mostly make boards: 1x4, 1x6, 1x8, 1x10 & 1x12. These eastern sawmills buy Eastern White Pine. Out west they most buy Ponderosa Pine and Lodgepole Pine. These are much smaller production mills than stud and dimension mills.
Lastly, there are sawmills that just cut hardwoods. Oak, maple, White Ash, Black Cherry, Popular, etc. These end up going to furniture, flooring, bowling pins, pallets, and many other things too many to mention. These mills are generally much smaller board foot producers than softwood mills.
SO, different species of timber go to different types of sawmills. Basically, whoever will pay them the most for the timber. Sometimes, that means logs from Canada come into the US and logs from Maine go into Quebec.
On the west coast there used to be mills in WA state that bought timber that was barged/rafted to them from Vancouver Island down through the Puget Sound to Tacoma.