I've never had a problem renting a AWD vehicle in an area that has lots of snow and ice. Rental car companies in the US don't provide snow chains, and it's unrealistic to think someone is going stop and buy chains and install them on a rental car. I just rented a car from Hertz in Canada, and I do think it described the car as AWD when I made the reservation. However, if it's not clear, I would do it the old fashioned way and call and ask.

If you are going somewhere snowy it’s likely they have appropriate vehicles. It doesn’t do anyone any favors for a bunch of tourists to try to drive a Pontiac sedan from Denver to the ski areas. When I travelled to Connecticut on business frequently I often was given a Subaru rental at Avis when in most cities they would have given me a Kia sonata