Hi everyone,
I hope this request isn't redundant, but I'm planning a trip to Seattle and need to travel in the lowest possible altitude due to health concerns. I checked with Amtrak and received different information, but according to one agent, Marias Pass is one of the higher altitudes on the trip. I'm not clear about the Cascades.

I'd also like to investigate the lowest altitude (northern or southern) trip by car since I'm hoping to move to Seattle this year and will need to bring my pets.

Any tips or info about where to purchase an elevation map would be so appreciated. I had surgery 9 years ago that strangely caused me to have some shortness of breath in high elevations. Never had a problem before. Thanks all!
Venus