William T. Vollmann hardly looks like one of the most ambitious authors of his generation. Walking on Haight Street in his rumpled jeans, ball cap and black T-shirt, shoulders bowed beneath a heavy backpack, he seems an older version of the street kids who still congregate in the tawdry heart of Haight-Ashbury -- young men mostly, carrying bedrolls, panhandling for change. In a lot of ways, these are Vollmann's people: outsiders, on the fringes, whom society tends to disregard. Outsiders have motivated his writing, from his 1987 debut novel, 'You Bright and Risen Angels,' which posits a war between insects and human beings, through his most recent effort, the monumental 'Imperial' (Viking: 1,306 pp., $55), which tracks another kind of conflict: the battles, real and metaphorical, that define Imperial County -- battles over immigration and water, identity, and the reach and limitations of political power. The book, which came out in August, is perhaps the clearest expression of Vollmann's career-long commitment to immerse himself in complexities. To write it, he spent 10 years visiting Imperial County, interviewing hundreds of people, reading history and public records, soaking up folklore. The result is a hybrid -- curious only if you're unfamiliar with Vollmann's work -- a massive, multilayered look at the border region of southeastern California, from the Colorado River to the Coachella Valley, Mexicali to the Salton Sea. Merging journalism and narrative, sociology and myth, the book is less about Imperial County than the place Vollmann calls Imperial, which exists most firmly in his mind. 'It may be,' he writes, 'that since this southeast corner of California is so peculiar, enigmatic, sad, beautiful and perfect as it stands, delineation of any sort should be foregone in favor of the recording of `pure' perceptions, for instance by means of a camera alone; or failing that, by reliance on word-pictures: a cityscape of withered palms, white tiles, glaring parking lots, and portico-shaded loungers who watch the boxcars groan by; a crop scape of a rich green basil field, whose fragrance rises up as massively resonant as an organ-chord.' At 50, Vollmann is the author of 19 books, including 'Rising Up and Rising Down,' a seven-volume, 3,352-page history-cum-ethical-investigation of violence, nominated for a 2003 National Book Critics Circle Award in criticism, and 'Europe Central,' a historical novel about mid-20th century Europe, which won a 2005 National Book Award. In such works he walks a line between extreme engagement and extreme detachment, eschewing conventional morality to approach the world on its own terms. Although he has lived in Sacramento for nearly 20 years, much of his early writing deals with San Francisco, especially the Tenderloin, which he explored in novels such as 'The Royal Family' and 'Whores for Gloria' or the story collection 'The Rainbow Stories.' These books take on the urban demimonde of prostitutes and crack heads with an unsettling mix of distance and empathy. In one piece in 'The Rainbow Stories,' Vollmann gets close to a gang of skinheads, withholding judgment, allowing them to speak for themselves. In 2007's 'Poor People,' an examination of poverty, he exposes the complicity of his subjects, while insisting that we view them with compassion anyway. As for how he arrived at this perspective, it started with the skinheads: 'I was interviewing them,' he recalls, 'and one was telling me about someone he had shot. I wasn't sure whether I should believe it, and then I realized: It doesn't matter whether it was true or not because this was what he wanted to tell me. This was the self he wanted to project.' That's an unsentimental vision, but if one theme runs through Vollmann's writing, it's that sentimentality is a way to avoid facing things for what they are. This too is the aesthetic of 'Imperial,' in which Vollmann is less an interpreter than, to steal a phrase from William S. Burroughs, 'a recording entity.' (He has also published a companion volume of photographs, more than 200 portraits of the people who inhabit the border zone.) 'My intention,' he says, over an energy drink at a Haight Street coffee shop named the People's Cafe, 'was to understand the place and bring it alive. Of course, absolute understanding is impossible, and therefore the book is a failure. That's OK.' Vollmann talks about his work with the same dispassionate air he brings to writing. He's measured, polite almost to a fault; when you ask a question, he considers it, really, before saying what he thinks. And he does say what he thinks. At Moe's Books in Berkeley earlier this year, he told an audience that 'Imperial' is 'the least pleasurable of my books to read, line for line.' That this is untrue adds one more layer to the story; it may be 1,300 pages and feature dense thickets of history, but 'Imperial' is surprisingly accessible, full of gorgeous prose. 'Bill is a great stylist, and this is his most beautiful book,' says Larry McCaffery, professor of English emeritus at California State University, San Diego, and the friend who, in 1997, introduced Vollmann to Imperial. 'Just read the sentences. I don't think he gets enough credit for how he writes.' (Begin optional trim) Vollmann's abilities tend to be overshadowed by the sensational aspects of his career. Partly, it's the length of his books, but even more, it's the fixation on prostitutes and street life, and his tendency to put himself in the line of fire. In 1982, fresh out of college, he went to Afghanistan to help the mujahedeen against the Soviets; his account, 'An Afghanistan Picture Show,' was published in 1992. In Bosnia-Herzegovina, in the early 1990s, he survived a sniper attack that left his translator dead. While researching his 1994 novel 'The Rifles' -- part of a seven-volume 'Symbolic History' of America called 'Seven Dreams' -- he spent two weeks at the Arctic Circle and nearly died of hypothermia. These were death-defying stunts even for a young man; a decade and a half later, the father of a young daughter, his balance impaired, the hair at his temples graying, he seems heavier, slower, if not exactly the worse for wear. (End optional trim) For Vollmann, the issue is not just writing but also how he wants to live. 'Last year,' he recalls, 'I was in Kurdistan in an area that had just been bombed. ... We were going up a narrow canyon, right before twilight. It was getting dark, and I was looking down at the path, and my glasses were all misted up with sweat. I was having a little trouble seeing my feet, and there was a bit of a drop. And I thought, `How much longer can I keep doing this?' And you never know. You either stop too soon or too late.' Vollmann makes this observation in his usual matter-of-fact tone, eminently reasonable, rational. It's that mix of empathy and distance again, that need to look at everything with an outsider's eye. For all the years he researched 'Imperial,' moving back and forth from what he calls Northside to Southside, he never learned to speak more than rudimentary Spanish, which required him to use interpreters. 'It's a deficiency in that if I want an intimate tete-a-tete with someone who might not want to talk in the presence of a third party, I have a difficult time getting it. But in every other way I found it to be a great advantage, because, for one thing, interpreters buy me time. If I'm interviewing someone, I have a chance to look into the person's face, look at the books on the shelf and get it all down in real time.' Vollmann has been criticized for such a strategy -- as he has for his habit of paying interview subjects, a tactic purists see as a violation of journalistic standards -- but 'Imperial' has more in common with the 'Seven Dreams' novels than with any straight work of ethnography or history; it's literally all over the map. Sprawling, kaleidoscopic, unstuck in time, the book attempts to re-create in language the unresolved nature of the place. 'There's no epiphany here,' McCaffery says, 'although about halfway through, it's pretty obvious that there's a thesis: California and the demise of the American dream. Bill uses a phrase, `the disease of capitalism,' to describe what happened to that remarkable place, rich farmland that became the poorest county in the state.' To get at this, Vollmann interweaves first-person accounts with interviews and textual research, playing with both fact and legend: statistics on immigration juxtaposed against the Chinese tunnels of Mexicali, underground spaces where 'many many Chinese as they kept saying, used to hide.' The tunnels are portrayed as apocryphal until Vollmann finds them, shifting the equilibrium of what we know and what we think we know. Nowhere is such a process more vividly rendered than in his discussion of water, which underpins 'Imperial' like a subterranean aquifer. 'When the Imperial main canal first started running water through it in 1901,' Vollmann says, 'there was a huge headline in the paper: Water Is Here.' As he speaks, his voice grows as insinuating as those words must once have been. In the book, that phrase becomes a rallying cry -- a promise and a lie and always a come-on, much like the history of the region itself. 'I kept wondering whether Imperial County was noble or crazy or doomed or stupid, or what in the heck it was,' Vollmann reflects. 'And people were talking about water all the time. I realized I didn't know where I got my water in Sacramento.' This, for him, was the turning point, the moment when he understood that he was looking at a story involving outsize players and elements -- Los Angeles, San Diego, Imperial County, the U.S. and Mexico -- that had been able to coexist for a while until their needs became too great. 'That's the old human story,' he says simply. 'That's the story of history, and it's the story of probably a human being too.' Here, again, we come face to face with Vollmann's tendency to look at the big picture and the human drama through the same set of eyes. In the case of 'Imperial,' that means thinking about the border, about immigration and economics, both in terms of U.S. agents who treat the region as a war zone, and the illegal immigrants -- 'bodies,' they are called by both the author and some who patrol the area because, as Vollmann notes, 'the instant people specialize, it's in their interest to dehumanize the people their specialized function operates upon.' This is not to imply judgment, Vollmann insists; he has a lot of sympathy for the individuals -- outsiders, on the edge of two cultures -- on either side. 'I have nothing against you, Dan,' he tells one INS agent in 'Imperial,' even as he writes, 'Here I had better tell you that in all the 10 years it took me to write this book, I never met a single Mexican who could muster up good words for the United States Border Patrol.' And if he sees the border as a political construction, a line on a map having nothing to do with geography or humanity, but rather with money, power, resources, he also recognizes that 'any country unable to control its borders cannot adequately enforce nor even define itself.' So, how to reconcile these contradictions? For Vollmann, it means recognizing their futility on the most existential terms. 'It does feel like a very durable entity,' Vollmann says, 'this place called Imperial, which existed before us and will outlast us. The history is really fascinating ... but I do feel that, in spite of its immense relevance to humans, humans aren't necessarily so important to Imperial.' (Begin optional trim) Meanwhile, in San Francisco, Vollmann heads over to Bound Together, the Haight Street anarchist bookstore where he picked up some of the materials he cites in 'Imperial.' Today, his tastes are less focused; he buys a postcard and a sex magazine. But as he browses, he seems to loosen up a little, as if he's found his place. 'I've always felt I want to be of service to the world somehow,' Vollmann says. 'I haven't yet figured out how to do it, and I may never figure out how to do it. But one has three choices. One can stay in one's own class environment, or one can say, `I don't like who I am and where I come from, and I'm going to become,' let's say, `a poor person.' Then, there's a Jewish proverb I've heard: `Out of any two choices, I take the third.' So I take the third choice.' (End optional trim) Ulin is book editor of the Times. 