I've also posted this on the Canada forum.

Is it possible to fly to Maine, rent a car and drive to Fredricton NB? We would return via the same route. If feasible, what city and route would be the best? We're thinking of traveling sometime before the winter sets in.

Yes, u can fly into ME and rent a car and drive from Maine to New Brunswick. Put the city you will leave from in Maine and Fredericton, NB into googol maps and you will see the routes you may take. You could fly into either Bangor or Portland with Bangor being the shorter drive of the two.

Be certain to ask the rental car company if you can drive into Canada, and if your insurance is valid for Canada.

The best route would be to fly into Bangor, then head toward Rt 1 and follow the coast road. Be sure to stop at Helen's in Machias (Maine) for apple pie. St Stephen, just across the border from Calais (pronounced "callous") Maine is a pleasant enough town.

Thanks for the info and tips. Didn't think about the rental car company and potential issues.

We've taken rental cards into Canada many times with no issues, but always good to ask.