I’m driving through these beautiful fields. I want to grab that corn like you’ve never seen. So rich, so beautiful,” Donald Trump told a standing-room crowd last July, at a Make America Great Again “family picnic” in Oskaloosa, Iowa. An obvious applause line, perhaps, but Trump delivered it with the aplomb of a man who had just taken the lead in every national poll. He was speaking to a crowd of about 700 people inside a high-school auditorium, and another 700 or so were standing outside in the overflow section. The appearance of this crowd was, not surprisingly, homogeneous, though one man who looked Latino sat on the bleachers behind the podium, well within view of the cameras trained on Trump. Before the speech, this man had been intensively stage-managed by Trump’s people: he was taken off the stage, given a properly logoed T-shirt, then reseated up front, stage left, nope, not quite, and finally reseated on the periphery, stage right, about halfway back.

While the man and the rest of the crowd looked on, Trump moved quickly from the pandering particulars to his generic stump speech, about a terrifying trip to the border (“My wife came home, and she was crying”) and murderous Mexican immigrants (“Such a big problem, and nobody wants to talk about it”). If Trump recognized the connection between the corn he wanted to grab and the immigrants he wanted to send home at Mexico’s expense, he didn’t acknowledge it. But I’d guess that nearly every person in that auditorium understood the contradiction: corn is America’s largest crop, Iowa grows more of it than any other state, and Iowa’s agribusiness depends on the Latino laborers who fill the towns that the Midwest calls “little Mexicos,” one of which was just twenty-five miles from where Trump was speaking.

This month, on February 1, Iowa’s caucuses mark the true beginning of the presidential-election season — the process by which the nation, at least in theory, has its say about the fundamentals of its existence. Trump was just one of twelve 2016 presidential candidates who toured Iowa during the two weeks I spent in the state last summer. The other nine who were then running would arrive within a few more weeks. Observers have long scratched their heads about the weird positioning of the Iowa caucuses, and every four years pundits declare that Iowa’s relevance to presidential politics has come to an end. (“Is Iowa Over?” Politico Magazine asked bluntly the month before I was in town.)

It seems to defy reason that this anachronistic farm state — a demographic outlier, with no major cities and just 3 million people, nine out of ten of them white — should play such an outsized role in American politics. But Iowa is not over. In fact, it may be more relevant than ever. Grasping the corn as Trump suggested leads us not just to the tensions of immigration but to all the central issues of the campaign — to health care and obesity, to our nation’s worst environmental problems, to poverty and income inequality, and to the entrenchment of a corporate oligarchy. We are what we eat — all of us, not just Iowans. Corn is the foundation of our bodies and our body politic, a truth that is more evident in Iowa than in any other place in the nation. Far from being an outlier, Iowa plays a central role in American culture. The weeks and months leading up to the caucuses represent the one time every four years when our political elite briefly acknowledges that fact.

William Stowe’s office sits near the confluence of the Raccoon and Des Moines Rivers, which were laid down by the Des Moines Lobe of the Wisconsin glaciation more than 12,000 years ago. The office was built there to superintend the piping and delivery of river water to half a million customers of the Des Moines Water Works. Stowe is the head of the organization. He trained as both an engineer and a lawyer, and lately has needed the latter set of skills. His utility has sued the county operators of drainage districts in rural Iowa in a case that is pending in federal court. Environmentalists nationwide view the case as a bellwether; it may well produce the legal precedent they need to solve a plague of continental scale. Many Iowans view the dispute as a battle between the city and the country; they see Stowe as a pariah.

“We have had death threats,” he says. “We’re the ‘radicals.’ We’re the ‘revolutionaries’ who are declaring war on rural Iowa. In reality we are protecting public health, and we’re protecting the economic viability of our consumers.”

The problem is simple enough. Rain falls on Iowa pure and clean, but it arrives at Stowe’s intake pipes a few hours later sufficiently polluted to violate federal standards for drinking water. Farmers have been raising corn and hogs in Iowa, and the people of Des Moines have been drinking river water, ever since the Civil War, but only in the past decade or two have the nitrogen fertilizers from industrial agriculture rendered that water undrinkable.

Under the current reading of the relevant federal law, pollution from a factory pipe is called “point source” and is regulated. If a factory or municipal sewage-treatment plant sends concentrated nitrates and phosphorus down a discharge pipe to a river, the feds will put a stop to it. Runoff from a farm’s field, “nonpoint source,” is not regulated at all.

Nationwide, any river or stream that wends through farm country suffers pollution to the point of death, but in the Upper Midwest, the plague is nearly total. Agricultural fertilizers traveling from the Corn Belt down the Mississippi River have killed a Connecticut-size stretch of the Gulf of Mexico that is now called the Dead Zone. Iowa occupies less than 5 percent of the land in the Mississippi basin, but it contributes 25 percent of the nitrate pollution responsible for the Dead Zone, almost all of which is attributable to farming.

In August 2014, Corn Belt fertilizer pollution led to a toxic algal bloom that poisoned the water supply of Toledo. John Kasich, Ohio’s governor then and now, alleged by some to be the thoughtful conservative among the Republican presidential candidates, responded to the contamination of a large city by calling out the National Guard to distribute bottled water. Later he signed a palliative bill, endorsed by Big Ag, that did nothing to sully his business-friendly reputation or to limit the phosphates and nitrates responsible for Toledo’s problem. None of this is mentioned prominently in his campaign in Iowa.

At least a third of Iowa’s farmland is underlaid with drainage pipes, like the veins of a hand. The same is true in much of Kasich’s Ohio, as well as in Indiana, Illinois, Minnesota, and parts of Wisconsin and Michigan. Again like veins, the networks gather fluid in bigger and bigger pipes that finally pinch together before discharging into rivers. The Environmental Protection Agency says that farm pollution is not pollution because it doesn’t come out of a pipe, but in Iowa, farm pollution does come out of pipes. Nonetheless, paper is waved over the water, a box is checked, and the toxic runoff is transubstantiated.

These days a fair amount of the nitrates are derived not so much directly from chemical fertilizers as from hog manure. There are about 21 million hogs in Iowa, and almost all of them live in hog factories. Each hog produces the waste of about 2.5 people, meaning Iowa bears the shit equivalent, from hogs alone, of about 45 million people, some fifteen times its human population. But Iowa also has 52 million laying chickens, 50 million of which are in concentrated animal-feeding operations (CAFOs) that hold more than 100,000 birds. These birds likewise produce more manure than all the people in the state. Almost none of it passes through a sewage-treatment plant or even a septic tank before making its way through drainage pipes to the public waterways and drinking water.

It is technically possible to remove nitrates from water, and this past year the Des Moines Water Works has been attempting to do that, at a cost of more than a million dollars. But the level and persistence of the pollution have repeatedly overwhelmed the equipment. Absent cleaner intake water, the Water Works will face up to a $180 million bill to upgrade its equipment, but this amount vastly understates the cost of the problem. There are 260 cities and towns in Iowa that face similar problems with their water supplies, and removing the nutrients from drinking-water intakes does nothing for the life of the rivers themselves.

There’s another way to fix the problem. It involves simple measures such as running farm-field drainage pipes into restored wetlands and permanent pastures instead of rivers. Ten acres of wetland can treat the runoff from 1,000 acres of hard-farmed corn. By timing their applications, farmers might also apply less fertilizer while still ensuring their yields. These measures do not mean growing less food, though they might require some different crops, maybe even raising a few cattle on grass. Scientists from the state’s agricultural department and Iowa State University have penciled out and tested a program of such low-tech solutions. If 40 percent of the cropland claimed by corn were planted with other crops and permanent pasture, the whole litany of problems caused by industrial agriculture — certainly the nitrate pollution of drinking water — would begin to evaporate. There are no technological or financial hurdles to implementing this program, but there is a political obstacle: the federal government would have to stop subsidizing the growing of corn. Between 1995 and 2012, those subsidies amounted to $84 billion.

At this point we would do well to remember that the time-honored mark of a developing country is that its tap water is undrinkable. Today, “Don’t drink the water” is sound advice in much of Iowa. Ironically, the American right wing has become especially fond of charging that the policies, real and imagined, of the Obama Administration have reduced the nation to the status of a banana republic. This complaint is especially prominent in discussions of immigration. Nationally, the chief fire-breather on this matter has been Steve King, the Republican congressman from Iowa’s Fourth District. He says that those favoring immigration reform “advocate for the destruction of rule of law and for anarchy and the descending down into Third World status.” His district happens to contain some of the state’s heaviest concentrations of hog factories, slaughterhouses, and restaurants where it is possible to find decent carne asada.

King wields a great deal of influence among Iowa conservatives, and for much of last year there was intense speculation about which presidential candidate would receive his endorsement. He has explicitly praised Trump for following his lead on immigration, but it was also reported that he went pheasant hunting with Ted Cruz, Mike Huckabee, Bobby Jindal, and Rick Santorum. (A pheasant hunter I met in Iowa told me that in recent years hunters have had to carry water for their dogs, lest they be poisoned by the streams made toxic by the same algal blooms that contaminated Toledo.)

Finally, in November, King made his choice. “I believe Ted Cruz is the candidate who is the answer to my prayers,” he said at a press conference. “A candidate whom God will use to restore the soul of America.” Among the candidates with actual experience in elected office, Cruz hews most closely to Trump’s views on immigration and many other matters, and he has proved the least willing to criticize Trump. While several Republican candidates expressed outrage at Trump’s suggestion that he wouldn’t rule out special databases for Muslim Americans, Cruz mustered only the following: “I’m a big fan of Donald Trump’s, but I’m not a fan of government registries of American citizens.”

Cruz has also distinguished himself in Iowa in a surprising way: he is the only candidate still in the race to come out unequivocally against the Renewable Fuel Standard, the federal mandate that all U.S. transportation fuel contain a minimum amount of renewable biofuel — which is to say, ethanol. Before 2005, when Washington introduced the standard, virtually all of Iowa’s — and the nation’s — corn went to animal feed or processed food. Now about 40 percent of America’s corn goes to gas tanks, the ultimate proof of the assertion that industrial agriculture is not about food. The ethanol mandate is imposed by the heavy hand of government in a manner that violates basic conservative principles, yet the requirement is popular among Iowan business interests, for obvious reasons. During the lead-up to the caucuses, Bruce Rastetter, an agribusiness mogul who has made millions on ethanol and is the state’s biggest Republican donor, organized what he called the Iowa Ag Summit, at which he personally gave a public grilling to nine of the Republican candidates on the issues of the day, which turned out to mean, for the most part, support for the ethanol mandate and laments about “overreach” by the EPA in matters such as Des Moines’s drinking water. With the exception of Cruz, each of the assembled conservatives had pledged varying degrees of support for a federal intervention that creates a market distortion.

Hillary Clinton and Bernie Sanders, her fellow Democrat, have also endorsed the Renewable Fuel Standard. In May, Clinton penned an op-ed for the Iowa Gazette confirming her support for the mandate and “other federal incentives that have been a success for Iowa,” which she said were central to America’s efforts to “lead the world in clean energy,” the evidence borne by Iowa’s rivers notwithstanding.

The day after Trump spoke in Oskaloosa, I passed Clinton’s motorcade, two black Suburbans and a white van marked staff, as it left the Des Lux Hotel in downtown Des Moines and headed north toward Ames on streets that wound between the Raccoon and Des Moines Rivers. Both were swollen and as brown as Bavarian chocolate because of catastrophic erosion from upstream farm fields. Now the rivers were too thin to plow and too thick to navigate — and certainly too foul to drink, polluted as they were with nitrogen fertilizers, pesticides, and hog shit.

Virtually all of the corn that doesn’t go to ethanol is eventually consumed by humans, but it usually gets to our plates by a circuitous route. One way or another it is processed. About 12 percent is funneled into industrial refineries that crack corn into its elements: starches and sugars — especially in the form of high-fructose corn syrup, the basis of the high-energy diet that makes so many people sick and fat.

It ought to be harder than it is to account for the American diet. There are, after all, thousands of edible domesticated plants, dozens of animals, and endless ways to raise, combine, and create food. The big picture, however, is depressingly easy to paint. American agriculture is corn, soybeans, wheat, and hay — four crops that account for 85 percent of the nation’s farmable land. In Iowa, corn and soybeans cover 23 million of the state’s 24 million acres of cropland. One presidential candidate has a literally visceral understanding of the health implications of this fact. Jeb Bush slimmed down substantially before hitting the campaign trail by adopting the popular paleo diet, which can perhaps best be defined as avoiding any of the food that Iowa produces. Yet he doesn’t talk about his personal and quite correct understanding of the country’s fundamental nutrition problem. Instead he ate a deep-fried Snickers bar at the Iowa State Fair, a ritual display of self-flagellation that has become necessary in a state where about a third of the people are obese.

The national obesity numbers are not much different, and there has been much bickering among nutritionists, an endless series of conflicting results from gold-standard randomized controlled trials, about the roots of the epidemic, which is responsible for as much as one in four dollars spent on health care in the United States. But there is a simple way to approach the question: we can account for the flow of food. Per capita U.S. consumption of protein and fats has not changed much over the past half-century. Per capita consumption of carbohydrates, however — sugars and starches and Snickers bars made from corn syrup — has risen consistently.

Meanwhile, though fat consumption has not changed in the past fifty years, the composition of the fats in our diet has changed drastically. When researchers tracked the American diet from 1909 to 1999, one commodity stood out. Per capita consumption of soybean oil increased a thousandfold. No other food came close to matching that number.

Soybeans are corn’s fellow travelers, grown by farmers not because there is great demand for veggie burgers, edamame, and tofu but because they complement corn in crop rotation. Most soybeans go to processed food and livestock. The component of soybean oil that is at issue in the obesity epidemic is linoleic acid, a fat that is common to many vegetable oils and ubiquitous in processed foods. Before the middle of the twentieth century, Americans got about 1 percent of their energy from linoleic acid; now they get about 8 percent. When researchers replicated that change in a diet fed to lab animals, with no increase in total calories, the animals became obese. When the linoleic acid was reduced, the obese mice became skinny. The scientists then bred four generations of mice and found that a fixed diet with a high proportion of linoleic acid produced more obesity in later generations. Linoleic acid belongs to a class of fats, the omega-6s, that have supplanted the other important group of fats, omega-3s, largely animal fats, in our diets. There is even some evidence that linoleic acid prevents our bodies from using what omega-3s we do receive from our food. Omega-3s are crucial for brain development. It is probably too cynical to suggest that food marketers planned a diet that compromised our intelligence, but at least they created a situation they can work with.

There is another way to process corn and soy for human consumption: feed it to animals. As a nineteenth-century observer wrote, “The hog eats the corn, and Europe eats the hog. Corn thus becomes incarnate; for what is a hog but fifteen or twenty bushels of corn on four legs?” Research shows that one of the biggest sources of linoleic acid in the American diet is chicken.

Iowans have one way of saying this: they lament that their state has been “chickenized.” You could more specifically say it has been “Tysonized.” Tyson Foods prefers to describe the process as vertical integration. A few decades ago, the company began to acquire every step of the process — from producing and delivering feed and hatchlings to slaughter, processing, and distribution — while also expanding horizontally. At the same time, the company almost literally redesigned the biological unit called a chicken, genetically selecting for animals that would gobble high-energy corn and soy to fatten rapidly while crammed in windowless, climate-controlled factories. The goal was a uniform flow of chickens to retailers, especially Walmart and fast-food restaurants. (Annual per capita consumption of chicken in the United States has more than doubled since 1969.)

The process depended on a networked system of growers and farmers, who became contractors. The network was organized as a tournament. Tyson delivered hatchlings, formulated and supplied the feed and antibiotics, and took away the birds when they were ready for slaughter. The company owned every step of the process except the chicken confinements. Growers in a given region were lumped in a pool and paid on the basis of a competitive scheme that ranked them according to the pounds of chicken produced per pound of feed. Everything was tightly monitored by a flow of data that measured corn and soy in, McNuggets out. A productivity gain of a few percentage points meant the difference between bankruptcy and a paycheck for many growers — several people I met in Iowa called them “serfs.” It is an interesting extension of an ancient process. As Charles Darwin wrote, domestication is nothing more than hypercharged natural selection. Tyson’s competition for survival reformulated chickens, but it also domesticated farmers.

Pork processors, the swine capitalists, saw chicken production begin to crowd them out of markets, and so they adopted Tyson’s model. They started in North Carolina, but almost immediately Smithfield Foods brought the change to Iowa. Tyson also got into the pig business. Now Tyson and Smithfield, along with three other corporations — JBS, Cargill, and Hormel Foods — account for almost three quarters of the nation’s pork.

In Iowa, the system combines with politics in a curious little diorama displayed on the outskirts of nearly every farm town. Alongside the usual national fast-food outlets, the state harbors a homegrown chain called Pizza Ranch, which has more than 180 restaurants in the Midwest. The chain offers several forms of industrial pork and chicken embedded in a matrix of cheap carbohydrates, but also satisfies a different need: Pizza Ranch “believes in the power of prayer. If you have a specific issue that you would like us to pray for, please send it in using the form below.”

Though Democrats used to visit Pizza Ranch in earlier years, the chain is a mandatory stop for Republican presidential hopefuls. The Republican contest in Iowa is really a struggle for the evangelical vote, which has slowly accumulated in Cruz’s corner. In December, he drew the coveted endorsement of Bob Vander Plaats, the state’s most politically active evangelical, which along with Steve King’s endorsement helped move Cruz past Trump in local polls. By the time of the caucuses, Cruz — and most of the other candidates — will have made multiple Pizza Ranch visits. Mike Huckabee told the Des Moines Register that he won the 2008 caucuses in large part through such visits: “We created the Pizza Ranch strategy. A lot of people have copied it since then, but I think we created it.”

This election cycle, klatches at the chain take place almost daily: a candidate in a suit (or jeans, depending on the desired optics of the day) scarfs a slice while ringed by ruddy men in ball caps, most of them obese, many of them corn growers, chicken growers, or hog growers under contract to a handful of corporations. There they speak about the problems that affect their lives, such as the coming imposition of sharia law. They also talk about the need for the federal government to “get out of the way” of free enterprise, especially their particular brand of federally subsidized free enterprise.

Chris Petersen is a farmer who raises a few hundred legacy-breed hogs in old-school conditions near Clear Lake. The day I visited him, however, he wanted to show me his chickens, a flock of hens that were pecking and wandering, uncaged and un-CAFO’d. Everybody with uncaged chickens wanted to show them to me, because Iowa’s chickens had recently made national headlines. The state has the largest population of caged laying hens in the country, and about half of them died last summer from an epidemic of bird flu. There were discussions in the press about whether it was more humane to exterminate infected flocks by turning off the ventilator fans and letting the animals suffocate or by covering the birds with fire-extinguisher foam to snuff them out by the hundred thousands. The total cost to Iowa for the epidemic would finally be estimated at $1.2 billion.

The traditional farmers I met wanted to show me that none of their chickens had died of bird flu. Avoiding the epidemic, they said, was simply a matter of not raising the birds in caged conditions. All of this went unmentioned in the presidential campaign, except by Carly Fiorina, who suggested that the way to deal with the problem was to find a faster way to deliver federal payments to chicken farmers who had lost birds. Fiorina also called the Des Moines Water Works lawsuit an example of government “overreach.”

Petersen is a political animal as much as he is a hog farmer, and he has been deeply engaged with presidential politics for decades. He’s on a first-name basis with Barack Obama and both Clintons, and stumped for Al Gore and John Edwards. And yet as we talked at his dining-room table, in the modest frame house that he’s lived in most of his adult life, within walking distance of the farm his Danish-immigrant grandfather bought with the money he made digging ditches for drainage tiles, he did not speak much about the campaign. Hillary Clinton would be just a few miles south that week, but Petersen showed no excitement, perhaps because the Clintons’ political fortunes were greatly aided in the early days by Tyson money; the two Arkansas dynasties arose in parallel. Bill Clinton was Tyson’s biggest political supporter, and he delivered the eulogy at the funeral of Don Tyson, the company’s former CEO. Hillary Clinton sat on the board of Walmart, the retail pipe for chickenization.

But Petersen’s disengagement likely had far more to do with something William Stowe told me: “Tom Vilsack has been a terrible disappointment.”

When Obama appointed Vilsack as agriculture secretary soon after taking office, it was a way of making good on his campaign promise to reform industrial agriculture. As governor of Iowa, Vilsack had been a supporter of reform, and as agriculture secretary he used antitrust regulation to challenge the Tyson-engineered tournament system. Tyson responded by joining with Smithfield and other meat producers to mount a multimillion-dollar lobbying campaign, complete with astroturf opposition and congressional arm-twisting. Big Ag outplayed Vilsack at nearly every turn, and he quickly backpedaled on the new rules. Finally, Congress killed the reform effort late in 2011. Two years later, with the fundamentals of its business plan intact, Smithfield sold itself to the Shuanghui Group, a Chinese company. What Smithfield sold to the Chinese was less its pork production than its control of Iowa’s politics and its landscape. The irony of some of the world’s last remaining Communists taking over from Iowa’s swine capitalists is outdone only by Donald Trump, who spends whatever time he isn’t using to bash immigrants bashing the Chinese. He offers no hint, of course, about how he might best the Shuanghui Group, which, through finely honed contracts, now controls the landscape of all that beautiful corn in the Midwest.

When Rubio, Walker, and Fiorina joined Trump in railing against China, they got personal, directing their fire at China’s president, Xi Jinping. Not long afterward, Terry Branstad, Iowa’s Republican governor, who serves primarily as a shill for Big Ag and is in all other matters philosophically aligned with the Republican field, issued a statement that took exception to the seditious talk. Schooling the candidates about the realities of who owns Iowa, he said that Xi “calls us old friends, not just me but a lot of people in the state of Iowa. That’s an important trading partner, so we want to keep that relationship.”

There is no doubt that conservatives would like to win the presidency, but they don’t actually need to. We have a naïve sense that to correct wrongs in our country, we simply need to elect the right president, pass the right laws, and that’s that. Politics in a state such as Iowa, however, teaches us that laws are only the beginning of the process, the opening bell for litigation, lobbying, and defiance. Faced with a federal mandate to regulate hog manure, Branstad simply cut the budget that paid for inspectors. Likewise, he roundly criticized William Stowe, urging Des Moines Water Works to address its issues with collaboration and volunteerism.

“What we see every time we hear ‘collaboration’ is buying time, a defense for the status quo,” Stowe told me. “The status quo will ultimately bankrupt our rivers and seriously jeopardize the public health of our consumers.”

Faced with regulation that will limit the carbon emissions that are killing the planet, Mitch McConnell, the majority leader of the U.S. Senate, a fellow who has sworn to uphold the Constitution, urged states to violate the law. The tightly organized, cohesive network that is the American right wing has abrogated the social contract with wholesale, institutionalized civil disobedience. Want to regulate the manner in which farms pump liquid shit? Sure. Can you do it with the twenty-eight inspectors Iowa has to oversee 4,000 hog factories, the pumping on which occurs almost entirely during a few weeks in autumn, and often at night?

The standoff that results from all of this plays out across our continent. Those endeavors that produce food and energy need scale and landscape and are of necessity rural and are of necessity unspeakably destructive. The industries involved must be free to operate on their own terms in the landscape in the nation’s midsection, where the states are red and square. As Stowe says, all they have to do is to protect the status quo. To do that, they don’t need to play to checkmate; stalemate and gridlock are success enough. Iowa’s caucuses, and for that matter the whole presidential ritual, will do nothing to change this.