Two states into his auditory road atlas of the United States, Sufjan Stevens has already run into critics speculating about the feasibility of recording an album for every state in the union. But to listen to the 30-year-old songwriter talk about the project, there is nothing in his voice that implies an urgency to reach the final destination. Asked if he's plotted his course across the country, Stevens is nonchalant. "I don't think I've developed a methodology just yet, but I generally want to go near the coast for the next record." (Still, rumors point to Rhode Island or Oregon, and a possible late-2005 release.) The unhurried approach allows for detours of a nongeographical variety (2004's Seven Swans), and gives him time to brush up on state histories between albums.

The project launched in 2003 with Greetings from Michigan: The Great Lakes State and continued with this year's Illinois, but, Stevens says, "the idea started much earlier, even before I was a musician. In civics class in sixth-grade, I was obsessed with the 50 states, and we had a puzzle map to help us memorize the states and the capitols, and the main industries and agriculture, and the state birds, and all the trivia." It was during an oral report on Oregon that he came face to face with the limitations of history as it is taught in school. "In my research I came across a book on Sasquatch/Bigfoot sightings in Oregon, and I included in my map local sightings of Bigfoot. It created this big controversy because my teacher felt that it was unreliable information and that it had no place in a history report."

His teacher's dismissal of these "facts" and the young artist's defense of their validity ("People reported these things, and I believe in them") struck a chord. "I started to think of our idea of history, and how we have different sorts of information and propagation that kind of inform understanding of our history and place. Some of it is manufactured — it's public relations — some of it is commercial, some of it is oral history, some of it is mythology, and I find that a lot of these sort of less conventional traditions are lost in today's media age," he says.

"In some ways this project is kind of my way of sort of gathering information and assessing it, and uncovering maybe stories that aren't told very often." Stevens' early fascination with the supernatural stemmed from natural childhood longing ("I never saw Bigfoot, but I wanted to") and a personal connection to extraterrestrials. "There were a few years when my parents thought that they were star people." The leadoff track on Illinois, "Concerning the UFO Sighting Near Highland, Illinois," documents the perspective of true believers. The words are as vague and open to interpretation as the event that inspired it, but the lyric "history involved itself" seems to encapsulate Stevens' belief in the importance of first-hand accounts.

Unlike on Michigan, the Detroit native had no residential experience of his own to draw on for Illinois, so he contacted Illinoisan friends, listened to their stories of the 4-H Club, and immersed himself in the literature and history of the Prairie State. "I read a lot of Carl Sandberg, Saul Bellow … I read a few biographies of Abraham Lincoln, and I was obsessed with Mary Todd for a while." The resulting 74 minutes are a perfect blend of personal narrative and historical fact all filtered through the artist's point of view, something Stevens admits was difficult for him. "I wanted to relinquish the autobiographical element on the record originally," he explains. "I wanted an emotional clarity and distance from the material." Even though most of the research for the album came from vicarious sources, Stevens found it wasn't easy to remove himself from his subject matter. "The more of it I wrote, the more I realized that everything was rendered through my experiences, and that I couldn't with real conviction write a song that didn't somehow incorporate real-life experience." Faced with a vast amount of information about a relatively foreign state, Stevens found he needed to "somehow feel an association" with the material in order to manage it and craft it into song. "I think that every song, even though it's about something in Illinois, is sort of reflected through a kind of autobiographical prism."

Stevens applies his personal slant on the Land of Lincoln to accounts of pageants and jubilees, but also to the state's seamy underbelly. "I read police logs from small towns," he explains. "You can learn a lot about a place from its petty crime." His method of pouring himself into his subject took a toll on his health when he delved into the life of a serial killer to write "John Wayne Gacy, Jr."

"I think that song is probably the most difficult song I've ever written. … For the few days after I had written and recorded it, I [felt] sick to my stomach," he says. The track is a quiet, delicate number that recounts the gruesome details of the murders and ends with Stevens confessing his own dark secrets. "I had kind of indulged a little bit in his story. I found myself part of that sort of American phenomenon in which we're obsessed with criminals, and there's a kind of voyeurism that we all have. And I felt really guilty about that." To ease his conscience, Stevens looked for "a way to sort of empathize with" Gacy. "I can't pretend to understand why he did what he did, and I'll never understand what motivates someone to do that, 'cause it's so completely sub-human, but… I wanted to somehow render him as humanly as possible. And the effects of that were pretty terrifying."

"Gacy," like much of Illinois, exemplifies the artist's coming to grips with "the discrepancy between how I remember [the Midwest] and what I imagine, and what it's really like." Having lived in New York City for the past seven years, Stevens allows that although he views his perspective as "somewhat privileged," he is still "inherently ideologically very Midwestern" and feels a connection with the region. "I have very strong allegiances to Detroit, to Michigan and… the surrounding states, but I find that when I visit, every time there's more and more of a culture shock." This disconnect is most evident on "Chicago," a song about leaving the Midwest in a van bound for the Big Apple. The uplifting chorus of voices contrasts with the narrator's solemn, mantra-like repetition of the phrase "I made a lot of mistakes."

Stevens plays more than 20 instruments on Illinois (he laughs when asked about the possibility of a one-man band: "I don't think I have the right center of gravity"), but there's a limit to what fits in a tour bus, and sacrifices had to be made. "The vibraphone did not fit last time, so we had to give that up. … I play a lot of woodwinds on the record, and I was trying so hard," Stevens continues, disappointment evident in his voice, "I brought the oboe and the recorders and the flute on tour, but it was just logistically impossible." Even after leaving his string quartet behind ("too expensive and too difficult to mic"), the Illinoisemakers (as he's dubbed himself and the seven members of his band) still have enough instruments to capture the lush, multilayered orchestration of the album.

Since before Michigan, Stevens has gathered material on other states for possible inclusion. "I have a kind of database right now. I have a collection of postcards and magnets. I have all the state quarters issued." The beauty of history is that it's always unfolding, and Stevens has all the time in the world to record his state-by-state oral reports before coming to the end of the road. As the saying goes, getting there is half the fun, and Stevens is creating essential driving music for the journey.

Sufjan Stevens plays Wed., Sept. 28, 8 p.m., $15, The TLA, 334 South St., 215-922-1011, www.thetla.com.