Alan Jackson photo courtesy of SonyBMG.

Locomotives aren't much about bluster. They're more about power, speed, efficiency, rugged beauty, and drive. So is the career of Alan Jackson, which recently passed the 20-year signpost without the slightest stall in sight. The country music superstar cites no particular ulterior motive in naming his new album Freight Train, although he will allow that maybe there's just the hint of a career metaphor in there. "This title just jumped out at me," he says. "When you really think about it, man, we've been rolling along here for a lot of years, still going like a train."

Momentum: you can't beat it, and Jackson's still got it. He's sold more than 50 million albums and had 34 No. 1 hits—three of those off his last album, 2008's Good Time. As superstars go, he's one of only a handful of artists who've been around for two decades who still regularly top the country chart. And unlike the other veteran smashmakers who can make that claim, he's the only one who is a true singer/songwriter, penning most of his own material.

Of course, there's nothing nearly so unusual about his combination of celebrity charisma and artistic craftsmanship when you consider him alongside his truest forebears. "I wouldn't want to compare myself to anybody," Jackson says. "But if I was going to say somebody I wanted to be like, of course, the two singer/songwriters in country music that stick out to me are Hank Williams Sr. and Merle Haggard. I don't know that there are two any better. I just don't put myself in that category."

Others might beg to differ, since Jackson's considerable catalog clearly positions him as a successor to these greats. He's celebrated the common man in "Little Bitty," "Where I Come From," "Little Man," and "Small Town Southern Man." He's spoken to the passing of generations in "Drive (For Daddy Gene)." He's addressed mortality in "Sissy's Song." He's treated the dream that country music itself represents with respect in "Chasin' That Neon Rainbow" and satire in "Three Minute Positive Not Too Country Up-tempo Love Song."

He can have hits with songs as heartrendingly meaningful as "Remember When" and hilariously meaningless as "I Still Like Bologna." He's spoken for a nation in "Where Were You (When the World Stopped Turning)," and spoken for the nearest barroom in "Don't Rock the Jukebox." He may be the only extant country superstar whose honky-tonk poetry can lead you to answer the eternal question, "Are you sure Hank done it this way?," with an unblinking, "Yup."

After penning every number on his previous album, Jackson wrote or co-wrote eight of the 12 songs on Freight Train, again showing the breadth of his emotional range. The opening "Hard Hat and a Hammer" energetically extols the satisfactions of manual labor. The comforts of long-term love and marriage get their due in the closing ballad "The Best Keeps Getting Better." If you're indulging a crush instead of a 30-year marriage, he's got songs for you, too: a cynic finds unexpected love in the frisky "I Could Get Used to This Lovin' Thing," which adds a steel guitar to a Tennessee Two-style boom-chicka-boom rhythm (speaking of trains). But heartbreak finds its way into the set, too, notably in a cover of the 1970s Vern Gosdin hit "Till the End," which unites Jackson with fellow traditionalist, Lee Ann Womack.

"If I had my way, the majority of it'd be sad," Jackson admits. "I love writing sad stuff better, whether I'm happy or sad, and they make much better records, usually, to me. The sad part about the sad songs is it's harder to get ‘em played out there! But also, I think about the people out there whose lives are already hard enough, trying to make a living. Everybody wants to hear something fun or that makes them feel good."

If Jackson has a reputation for writing songs that skew more toward contentment than sadness, that has less to do with satisfying audience expectations than just adhering to the "write what you know" ethos.

"I'm a real visual person, and when I'm writing, especially if it's a story-type song, I visualize what I know," he explains. "It's much easier if you write about something real. If I pick something that didn't sound like what I'd written or was part of what people think my life is, it probably wouldn't ring true, you know?"

Which doesn't mean these are diary entries. "When I write something like ‘After 17,' you could say, ‘Yeah, he wrote that about his daughter.' But I try not to write them so specific that it couldn't be about anybody's child, so they can read that into their own lives as well. In ‘The Best Keeps Getting Better,' I did use a lot of images from me and Denise, and everybody can see it's her in there. But I don't think it's so direct it couldn't be about anybody that's been married for quite a while.

"Once you start sharing your life in your music, then it's hard to get away from that. After ‘Drive,' people started looking at me like every song's about my family or faith, and I keep telling people, man, you've got to go back and listen to all my albums. They've always been collections of songs about my life, or my family—and then there'll also be songs on there that are drinking songs or heartbreak songs. I've always wanted each album to be a collection of all the things that to me are country music."