Did you see my comment about how she defined her sound? "Rock-tinged Country".
I hear quite a bit of Rock influence in her music and she has pointed out that Tom Petty and Springsteen are as important to her sound as Classic Country. Having recently bought and listened extensively to three of her CDs, I’d argue there is also an element of Folk present. Yes, some of it sounds more Country than anything else, but the lyrics are more sophisticated than most Country (avoiding the cliches so enamored by Country songwriters) and furthermore, display a notably introspective quality that tends to couch situations in shades of gray, rather than black and white. It’s here, in the lyric writing, that I detect a Folk or singer-songwriter influence. That said, I’m no longer sure it is Americana. In fact, the more I’ve thought about it, the less sure I am about what exactly constitutes Americana.
What’s your definition? I'm confused by your mention of Shania Twain. What I've heard by her is stylistically, writing-wise and production-wise, a very long way from Roots genres.