Sufjan Stevens has set himself a seemingly impossible task - write and record 50 albums built around every State in America. Two down, 48 to go. Jim Carroll meets the would-be novelist whose motto could be: have guitar, will travel.

Three cheers, please, for one singer-songwriter who believes that ambition is nothing to be scared of. After all, it is not every musician with a battered guitar who will merrily embark on a project to produce a series of albums eulogising every state in the US - and at the same make albums that a large and appreciative audience will be as keen as mustard to hear.

Having begun in the great state of Michigan (Greetings from Michigan) and taken in the wilds of Illinois (Come On, Feel the Illinoise), Sufjan Stevens shows no signs of running out of steam or inspiration as he contemplates what's to come. Indeed, he seems to be warming up as the miles accumulate and he flicks through more pages in his road atlas.

Current album Illinoise is a huge endorsement of the creative muscle of his 50 States project. A breath-taking ride through 200 years of history and characters, it is lyrically enticing and musically bracing. While the music hall flourishes and frills ham it up like a night out with Rodgers and Hammerstein, the songs Sufjan sings are grounded in the lives of those everyday folk living in towns like Jacksonville and Little Egypt.

"I've had some conversations with friends from Illinois," he says. "And they admire the extent to which I tried to incorporate small towns and traditions from farming towns and ghost towns. A lot of people misunderstand Illinois to be just Chicago. It's a lot like how New York City seems to eclipse the rest of the state. I'm more interested in the working-class story, so I felt that my attention fell below the centre of the state to some of those lesser known towns."

The project is audacious (if not a little daunting) and Stevens accepts that it could well escalate out of control by the time he hits Utah or North Dakota.

"I mean, if you think about the entire project, anxiety will eventually set in. It's inevitable, isn't it? But I never intended to make propositions to incapacitate myself. I feel like it is very open-ended and allows for a lot of room for experimentation."

He believes the project will allow him to perfect his craft as a songwriter. "Up to now, I think my songwriting for the project has been somewhat conservative and traditional. They're just narrative songs about the place in question. But I've been brainstorming and I have a lot of other ideas I want to try out. I want to try doing soundscapes or songs about the landscape. I don't think it will be just one thing in the future."

Stevens sees signs of progress in the new album. "It's a broader survey than Michigan, it's more optimistic and I think the writing is a little stronger. I don't know whether the songs are good or better or whatever but, in terms of the technique and the craftsmanship that I put into it, I think it's a lot more focused."

He's also happy with the breadth of musical sounds which are to the fore on the new album. "I wanted to create a real musical pageantry by incorporating some diverse sonic elements. But I also wanted it to be balanced with the smaller, quieter folk songs. I think, looking back at it now, what I was going for was the widest, possible emotional spectrum.

"It was taking into consideration the beginning of time, the here and now, historical events, personal events and autobiographical detail. I wanted it to be about civilisation generally, but also about me personally, so it's kind of soothing and flourishing all at once."

Originally from Michigan, Stevens first landed in New York to study creative writing. Words were always going to be his bread and butter, but he soon found that they sounded better when put to music rather than left on the page.

His first recordings appeared on Asthmatic Kitty Records, a small label set up by Stevens and his father-in-law to record and release music from around their home in western Michigan. A collective of artists soon emerged, with Stevens as the leading man.

He still views music as something of a distraction from what he really wanted to do. "Well, I came to New York to go to school, I went on to work in publishing and I wanted to write novels and get published and teach writing. That was my aim and I was sort of involved in that literary environment in the city for a while. The music thing was always a hobby, but at this point, it's obviously taken over my life. It's my career now, but writing remains my first love."

There is a symmetry between writing fiction and writing music, as Stevens has discovered. "Yes, they're very similar. They require different skills, and different ears, but there is a certain music to fiction, to the sentence and the rhythm of words put together. I think it's the same in songwriting as well."

The grounding in fiction writing probably explains his forensic approach to researching US states. He started out by writing songs about Michigan, a state he had lived in, but capturing the sound of Illinois required a lot more digging. This involved talking to state natives, reading Saul Bellow, studying accounts of early immigration, immersing himself in the biographies of Abraham Lincoln and unravelling the histories of various small towns.

"My approach is to do a lot of observing, reading, listening and questioning. It's the same kind of research you do when fiction writing. It has so much to do with your own personal history, your own experience, your own relationships. OK, it may be an one-sided, unbalanced view of a place, but it was never my point to create a comprehensive historical survey of a state. It's really about my voice and my personality and my character. That's what everything hinges on."

The public response has encouraged him to keep writing. "I'll be honest, I'm still a little shocked by the interest in what I am doing. My first audience is myself and it's very surprising to be considering a much larger, more public audience. I'm grateful that people have open ears and open hearts. I mean, it was a thrill when I started playing when there was more than one person in the room! Now, I'm playing much larger venues, and I don't recognize anyone in the crowd.

"It's very inspiring, but also a little confusing. I don't think musicians are ever quite sure how to manage that because I think it changes the way you have to approach your music and live performance. So, for now, it's a distraction and I'm dumbfounded by the response to what I am doing."

He's already set his sights on the next states in the series. "I've been doing a lot of research for Oregon, Rhode Island and New Jersey. I've accumulated a lot of stories and details, but once I sit down and start writing, I think I will be surprised by what starts coming out. That's always the way."

Sufjan Stevens plays Spring & Airbrake, Belfast on October 13th and The Village, Dublin on October 14th