Sufjan Stevens has a secret to share: There are moments in his life—particularly when he’s posing, and finds himself playing a role he does not momentarily believe—when he might as well be a serial killer. He delivers this revelation in a tremulous whisper during the final minute of the devastating Illinois track “John Wayne Gacy, Jr.” In 1978, Gacy—a part-time clown who went by the name Pogo—confessed to the murder of nearly three dozen young men outside Chicago. Stevens doesn’t forgive Gacy, per se, but he does find empathy in the Killer Clown’s biographical details, and in the woes that pushed him toward acts so heinous. The past and present force us all to wear masks, Stevens reckons (though we don’t all wind up killing 33 kids as a result). The saga of Gacy is but one bit of history that Stevens invokes during Illinois, the 2005 album that marks the second—and, for now, final—entry in his series about American states (the first, Michigan, served as his breakthrough upon its 2003 release). Illinois finds Stevens traveling throughout the Prairie State, from the 1893 World’s Fair in Chicago—where Cream of Wheat was unveiled—to a flood-prone graveyard full of Civil War dead to Jacksonville, a town named for a slave-holding president (and one that, ironically, became a hub of the Underground Railroad). It’s an album that functions as an elliptical and selective history of a place. But Stevens was never really writing about just a state. As heard on “John Wayne Gacy, Jr.,” these songs are opportunities for Stevens to sort through ideas about himself, his country, his family, and his outlook. After all, the album’s anthemic centerpiece, “Chicago,” is a personal history with the city, but not of it—a reminder of all the romance and drama a place so big can offer a young person. And while Stevens’ music has never lacked ambition, Illinois found him pushing himself not just emotionally, but musically. He was disappointed in some of Michigan’s compositions, telling the magazine Under the Radar in 2005 that he “didn’t feel like [he’d] achieved” some of his creative goals. And so, Illinois glistens and wows, from the dizzying motion of “Chicago” to the stomp-out-loud heroics of “The Man of Metropolis Steals Our Hearts.” In an instant, Stevens can turn from hushed folk for fans of Nick Drake, to maximalist pop informed by the minimalism of Steve Reich. It is little wonder Stevens’ Fifty States Project stalled after this; it’s hard to imagine how to improve on the glories of Illinois.