Sure, Tripper. You hand the completed AS form to a conductor on the Cascasdes or Coast Starlight train for processing. Forms are available at staffed stations (Seattle, Portland, etc.) and onboard the Cascades train. Coast Starlight is eligible, but I wouldn't be so confident they stock the forms. If you can't find any, or they don't post to your AS account within a couple of months, you can send photocopies of your boarding passes directly to Mileage Plan for credit.