“My musical quest [is] to get more and more purity into the music.” That’s something Tom Petty told me over the telephone once. Years later, I wonder if he died — on Monday in California at age 66 — pushing that boulder uphill. Because it was always the impurity of Petty’s music that made it feel so sublime.

Even back in 1970s, when he was just a blond smirk in a black leather jacket, Petty’s brand of Americana was already exuding its own mood, its own smell. As handsome as they were, his rock-and-roll songs came coated in a thin residue of psychedelic strangeness. And they still glisten in the light.

Some of it had to do with Petty’s thing for electric guitars that jangled and wheezed, and the rest of it had to do with his voice — an unmistakable mewl that could sound vaguely sinister, gently pleading or stylishly aloof. All the while, his songbook seemed to move across the map like a vagrant weather system, fluctuating from heartland warmth to California cool to whatever dank vibes must have been hanging over Florida when Petty first marched his Heartbreakers out of Gainesville in 1976.

His songs were well suited for ubiquity, meaning they often found their way to you. Maybe you first encountered his voice while hot-boxing to “Refugee” in the passenger seat of your buddy’s Camaro circa 1979. Maybe you found Petty loitering in Wonderland when the video for “Don’t Come Around Here No More” landed on MTV in 1985. Maybe you heard “Free Fallin’” on the radio 10,000 times in the autumn of 1989. Or maybe — and pity your soul — you first heard 1976’s “American Girl” more recently, once boomer politicians made a habit of pumping it on the campaign trail. Which is all to say, we probably consider Petty’s music to be quintessentially American because it wafted so easily across so many different American moments.

Petty rose to renown alongside similar American boys making similar American noise — Bruce Springsteen, John Mellencamp — but unlike those blue-jeaned alphas, he used the powers of MTV to burnish his image as a troubadour burnout whose closet happened to be overflowing with cool sunglasses and freaky top hats. Looking different helped make Petty a superstar in the 1980s, but sounding different is what made him last.

Even when he tried to straighten his edges, his music refused to give up its bends and curls. The mild warping on 1994’s “Wildflowers” is the very thing that keeps such a handsomely understated solo album from sliding into an exercise in tastefulness. And how close were you listening when Petty sang “I Won’t Back Down” at the Super Bowl in 2008? Go find the footage and you’ll hear his voice do something impossible: It quivers with certainty.

For a blast of the known and the unknown, it’s hard to beat “A Thing About You,” a hard-charging love song from 1981 about intense yearning, plus all of the obscure feelings that haunt that kind of desire. “I’m not much on mystery,” Petty sings in the opening line, but it’s already too late. The mystery is all around him. From that point forward, the harder he tried to blast through it, the more of it he seemed to gather.

Chris Richards is The Washington Post’s pop music critic.