BN's Trinidad Loop is worth checking out. It's about 5 miles west of Quincy. There were about a dozen MILW SD40-2 on loan to the BN after the MILW expired.
Documenting the comparative traffic of the Burlington Northern, the Milwaukee Road, and the Union Pacific between Puget Sound and the Midwest, mainly focusing on the 1970s but including other time periods as well. Also featuring Milwaukee Road freights on