The pivotal American Idol moment for Carrie Underwood was when she teased her hair to the heavens and sang Heart's "Alone," belting out the power ballad with sincerity and a natural flair for drama.

It was the surest sign that Carrie wasn't merely the country star the show gladly pigeonholed her as, that she was a pop star by any measure.

Of course, the great irony was that Carrie had little interest in being a pop star; she wanted to be a country singer, but the sheer magnitude of American Idol meant that she was already a pop star who needed to cross over to country, a reverse of the usual crossover move.

Underwood pulled off that tricky maneuver with a deceptive ease on her 2005 debut, Some Hearts, which turned into a smash success, turning sextuple platinum at a time when many albums struggle to go gold, even surpassing the sales of the original Idol, Kelly Clarkson.

Such success raised the bar for her 2007 follow-up, Carnival Ride.

Traditionally, second albums are a place where artists consolidate their strengths or expand their reach, either with an eye toward artistic growth or commercial success, and Carrie chooses the former option, creating a record that is more purely country than her debut.

She dials down the pageantry drama that peppered her debut -- there are no Diane Warren songs, for instance -- and plays up her humble, all-American persona, singing songs about small towns and big dreams, even attempting to kick up some dirt and grit on the one-night-stand anthem "Last Name," which is Miranda Lambert filtered through Shania Twain.

And one of the striking things about Carnival Ride is how completely Carrie Underwood has stepped into the void that Shania and Faith Hill left behind: the small-town girl made good but who hasn't left her roots behind.

In other words, she hasn't made the big pop diva move that Shania did with Up! or Faith with Cry; she's planted herself firmly within country.

Now, Carrie's country is hardly traditionalist -- despite the lack of Diane Warren tunes, there are plenty of power ballads here, along with light drum loops that aren't commonly heard in Nashville -- but her approach is completely contemporary country, in how it blurs the borders between country and arena rock, something that's perfect for a girl who made her first big splash singing Heart.

Sound and feel do mean a lot, but country records really survive on the strength of their songs, and the remarkable thing about Carnival Ride is that it's stronger song for song than Some Hearts, some of this due to Carrie herself, who bears four songwriting credits here, often in conjunction with some permutation of Steve McEwan and Hillary Lindsey, who pen a bunch of other tunes here.

The songs may veer just a bit too close to the big power ballads, but they all work as strong pieces of commercial country, built on surging melodies (all the better for Carrie to belt) and lyrics that play into Underwood's small-town girl persona but are also open-ended enough to be relatable.

All this very well may be more calculating than it appears, but the appealing thing about Carnival Ride is that it plays so smoothly and assuredly that you just go along for the ride, especially because Carrie sells these songs completely, making the clichés and cornball phrases believable.

It's a gift that Shania had, but she always seemed larger than life.

In contrast, Carrie Underwood only sounds larger than life, and she still comes across like the girl next door despite her massive success, and this lingering sense of innocence -- however constructed for stage it may be -- gives an album as big and shiny as Carnival Ride the appearance of a genuine heart, something that no other big country-pop album has had since the glory days of Come on Over.