It looks as though 99W used to go through downtown Portland and end at I-5 near the WA border? Cool!
Yes. The Thomas Guide showed this through the 1994 edition.
Of note, the Hampton Roads, Miami and Anchorage Street Finders were never Thomas Guides. They're strictly RMN.
But, the Boise Snake River Valley, Reno Tahoe, Olympia, Salem Central Willamette Valley, Spokane Coeur D'Alene and Kitsap County are all branded as Thomas Guide using the craptastic RMN symbology. Whereas the DC/Baltimore area Thomas Guides got rebranded as RMN but retained the Thomas Guide sympbology, though RMN switched to their dreck in the latest DC edition.
Also, RMN attempted to switch Portland and King/Pierce/Snohomish to their noise, but it annoyed enough people that they switched back to Thomas Bros symbology for the latest (now almost three years old) edition. The Pacific NW Atlas, however, got switched.