Aussies needing help
 

We're a family of three Aussie's travelling to Billings Montana to see Little Big Horn, then heading to Medicine Hat Alberta to see some friends, then going on to Vancouver by air. W though tot would be easy to hire a car in Billings and drive to MH. But guess what? - the car rental companies won't let us to a one way trip and drop off in MH. We have tried everything we can think of - bus, train, even Uber - but it's either too long or too expensive. Can anybody suggest anything please???

Yes, it's pretty much a non-starter to pick up a rental car in either U.S. or Canada and return it in the other country. But you could fly. I'd suggest flying into Calgary perhaps, since all the flights I see connect there anyway, and I'd imagine it's cheaper than air all the way to MH. Pick up your rental car in Calgary. But, from Billings, I'm pretty sure that your first connection would be a major U.S. airport like Denver, Seattle, etc., and then on to Calgary (and then Medicine Hat, if you wish).

I tried finding an air route back from Billings to Vancouver and then turn the MH - Vancouver ticket you already have into a return ticket from Vancouver. But as Sludick says flying out of Billings takes you somewhere else before Vancouver.

Down at the bottom of this link there is something called "Trans Border Service". Might be worth an email.

http://airportshuttleexpress.com/waterton.htm#moose

Many thanks to all who replied - much appreciated. In the end we chickened out and re-jigged our schedule. We'll drive to MH, then back to Billings to drop the car off - what a pain - then Billings to Seattle by air. Things like this should be a little easier in the 21st Century! Thanks again.