What is the best way to search for ground travel fares, for vacation trips?

travel
BK C asked:

I’m considering doing ground travel to a place not too far away from here. Air travel is too expensive (especially since my trip won’t be too far into the future) so I’m considering going by train or even by bus (train is preferred.)

How do I go about searching for travel fare? I’m hoping there is a site similar to Priceline or Travelocity that deals with ground travel of this sort.

DETAILS: I’m hoping to travel a round-trip vacation between Portland, Oregon and Calgary, Alberta (Canada, of course). I’ll be travelling sometime this month.

Once again, I’m looking for help with finding places to get trainfare (or anything with ground travel) be it a Priceline-similar site or anything. I just need a way to find and compare prices for travelfare. Any hints, ideas, suggestions? Any help is much appreciated!