What are the two major mountain chains that border the great mid-continental basin?

If you are referring to the U.S./Canada ranges, then I would guess the Rocky Mountains and the Sierra Nevadas are two major chains of Western North America. But, they are not the highest... simply the more well-known.
The St Elias Range in Canada has Mount Logan in it... the highest in Canada, the 2nd highest in North America and
Mount McKinley, in the Coast Range in Alaska being the #1 in North America.

The beauracrats in Ottawa once suggested to re-name Mount Logan in honour of Pierre Trudeau. That was quickly shot down.