In your case LAX-PDX-CHI-BOS is a valid routing so you can book it as a 3 zone reward. SubwayNut's recommendation is the way to go for routings that do not come up on Amtrak.com. It is also a great option if you want to spend one or more nights in a zone boundary city.You can force it yourself!
A 1 zone reward is 15K, a 2 zone reward is 20K.
The zone boundary on the Empire Builder is Wolf Point Montana,
Enter your email address to join: