That is good unexpected news,
I have been in the area a few times, motivated by an interest in history and of course the rail line. Not long after the last visit, the fortunate acquisition from a Seattle estate sale was unexpected too. It being a leather bound WI&M freight book detailing damaged goods delivered to Potlatch, Idaho customers. The book covers the entire history of the WI&M railway, 1905 until being acquired by the Milwaukee Land Co. in 1960. Adding interest is each item has the claimants names and their business. Most were very small amounts and in the latter years the entries decrease by the year.