This has been in my inbox for a while, but in 2009 Amtrak Cascades experienced a slight decline from the high gas prices and lower unemployment of 2008 while maintaining healthy gains over the recent past. According to the report, the drop in performance is mainly due to the Portland-Eugene corridor. In total, Cascades trains carried passengers about 118m passenger miles.
On a somewhat related note, if you participate in RailPlus — using regional passes to travel on Amtrak between Everett and Tacoma Seattle — you must obtain a “validation ticket” from the TVM with your ORCA card. Amtrak staff presumably don’t have ORCA readers.