This is Part 1 of a series looking at the people and scenery along the route of ExxonMobil's Pegasus pipeline, which spilled an estimated 210,000 gallons of heavy Canadian crude oil into the town of Mayflower, Ark. Read Part 2.

LITTLE ROCK, Ark.—The oil that erupted in the town of Mayflower back in March began its trip in an Illinois hamlet named Patoka, 90 minutes east of St. Louis. It shot down ExxonMobil's 20-inch Pegasus pipeline, under farms and forests, over the Mississippi River via a state highway bridge, through the Missouri Ozarks, across the Arkansas state line and, a few miles later, near the workplace of one Glenda Jones, whom you can find on a summer Saturday at her bar job, watching the Cardinals thump the Cubs.

The other bartender here at the Rolling Hills Country Club in the town of Pocahontas is named Brenda, so anyone visiting the golf course in far Northeast Arkansas is bound to meet one of the Endas, as they're known around the club. At 5 p.m. it's quiet in the 10-table lounge but for a Fox broadcaster making Jones's day: "Molina deep ... back to the wall ... it's gone!" Jones, the proud Enda and part-time house cleaner who refers to the Cardinals as "we," hollers, "Yes, finally!"

Ask Jones about Pocahontas, and she's quick to tout its famous five rivers (the Spring, the Black, the Current, the Fourche, the Eleven Point). And the people are sure friendly. "Course they are," she says. "We're in the middle of the Bible Belt. Know what I mean? Everybody's nice here." If one thing gives her pause about this area, it might be the Pegasus. It runs right under her yard, and she worries about it rusting. "Stuff like that only lasts so long," she says.

The Pegasus spill surprised people in Mayflower, in part because many of them had no idea they were living atop an oil superhighway. So we got to wondering: Where else does the Pegasus go? To find out, we traced its path using maps publicly available from the federal agency that regulates pipelines, the Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA). We got precise with Google Earth, following the pipeline's easement — the broad, bald line where trees are kept off the pipe — through the 13 Arkansas counties the Pegasus crosses on its way to Texas. From satellite images, we could see what another break in the Exxon pipeline could threaten: pastures, national forest, rivers, creeks, homes, churches, at least one school, this golf course. It also crosses watersheds for 18 drinking water sources that, together, serve about 770,000 people, a quarter of the state's population.

(Map by Lindsey Millar and Bryan Moats. See a larger version of the map here.)

The 858-mile Pegasus, now well into its seventh decade, has lain unused since March 29, when it burst open in the otherwise pleasant Mayflower neighborhood of Northwoods and belched up 210,000 gallons of heavy crude, by Exxon's tally.

The old pipe spends most of its time underground and is, in any case, just a long, steel conduit, without much character. Ah, but the places it traverses in Arkansas — nearly 300 miles of them! — are full of characters. They've lived with the pipeline underfoot since the 1940s, so long that many have never given it a thought. Many Arkansans we visited — Glenda Jones among them — didn't realize until a reporter called that their local pipeline was the same one that cracked open in Mayflower. And because they're living on top of a pipeline that's now been shown to crack itself open with no apparent provocation, and which a forensic report after the spill cited for manufacturing defects, they get to wonder the obvious.

"If it burst, right here, right now?" asks Derik Fitzgerald, the 0voluble golf course superintendent, at the Endas' bar. "What do you do?"

Fitzgerald knows and respects the Pegasus. Tuesdays and Thursdays Exxon flies a plane over to scope it out. One time Fitzgerald and another man on his crew were fixing an irrigation line maybe 40 feet from the pipe, on Hole 5, when Fitzgerald's friend heard the plane turn. "He said, 'That plane just seen us doing something.' "

They got a friendly visit from an Exxon rep after that one, just to be sure they knew to call in any projects within 200 feet of the pipeline. They also got a visit the time a flood piled branches and logs against the exposed pipeline in a creek. Fitzgerald called, and Exxon was out in a jiffy, yanking timber off the pipe and supervising the burning of the brush.

"I hate to take up for oil companies, I hate it," Fitzgerald says. "But they seem like they're on top of it." When he needs to notify the company that he's working near the pipe, Fitzgerald rings a guy. In his cell phone the contact reads "Billy Exon."

The trip from the clubhouse to the Pegasus takes five minutes. Fitzgerald steers a golf cart down a knobby asphalt path, through hairpin turns between trees, and to the creek where the pipe is exposed, parallel to a little bridge. It's a mottled, muddled thing, speckled with lichen and splotched with some tarry coating.

When the pipe was operating, 4 million gallons of crude would shoot through here at a pressure of 700 or 800 pounds per square inch. The crack that opened in Mayflower was some 22 feet long, roughly the length of this exposed segment. If there were another break, odds are people here would know it before the pipeline's built-in remote sensors. PHMSA records show that of the 960 spills in the United States between 2002 and 2012, sensors caught only 5 percent. Oil company employees found 62 percent. The general public reported 22 percent. That makes people like Jones and Fitzgerald part of the state's first line of defense in a spill.

Fitzgerald heads back to the clubhouse for a Reuben with blue cheese dressing and to order a Miller Lite from Jones. As he picks his way through the trees he ponders life in Pocahontas. "Play golf and drink beer," he says. "And call for a driver. ... Thank God for wives. Understanding wives."

Lawrence County

Two months after the Mayflower spill, Nathaniel Smith, director of the Arkansas Department of Health, sent a letter to Exxon and PHMSA asking that the pipeline company and federal regulators act on eight measures to guarantee that the Pegasus pipeline does not harm the 18 watersheds from which Arkansans drink.

Those recommendations include removing the pipeline from critical drinking water sources and installing isolation valves and protective encasement of the pipeline at all stream crossings. The letter also called on Exxon to update its emergency response plans and stockpile enough equipment to address spills promptly and thoroughly.

Jeff Stone, director of the health department's engineering section, says the state felt obligated to speak out after the spill. "Mayflower was a wakeup call for everyone," Stone says.

One of the water sources in northeast Arkansas is the Spring River, which the Pegasus crosses just before the Spring dumps into the Black River. When the hazardous materials team in Lawrence County considers the possibility of an oil spill, that near-convergence of the Pegasus, the Spring and the Black emerges as a particular bugbear.

"As firefighters, emergency response here, we don't clean anything up, we just try to stop it as soon as possible," says Joe Chappell, the medical officer for the county's hazmat team. "We mitigate the circumstances with it and wait for professional teams." They hold classes, they stock booms, they stay ready. The county hasn't been through a pipeline break, but it has seen a couple of train derailments, and an overturned propane truck that prompted the evacuation of a nearby school but which did not, thank goodness, explode.

"We always considered ourselves real lucky," Chappell says.

The Little Red: Milepost 366

Lowell Myers apologizes for his murky river. "This is normally crystal-clear," he says, but high rains have brought in mud from the hundred-odd upstream creeks that empty into this world-class fishery. Myers has guided here full-time for three years, and, for the 18 years before that, part-time while he managed the business side of Downtown Church of Christ in nearby Searcy. In the house of God, Myers spent his weekdays futzing with spreadsheets. He loved that job, but now he gets to guide people from all over the country, 12 months a year, on the river. "There's a great quote, and I can't remember what it is," he says. "Something about being in church, thinking about God, and being outside, being with God." Close enough.

Myers is heavyset, with an easy smile and snowy stubble that glints against deeply tanned cheeks. His flat-bottomed boat is 21 feet long and seats three comfortably. He backs it down the ramp at Ramsey's Access, a launch point on the Little Red River downstream from Pangburn. A blue heron loiters on a log as Myers aims the boat downriver.

The river is low, and the pregnant clouds overhead suggest why. With so much flooding downriver, the U.S. Army Corps of Engineers isn't releasing water from Greers Ferry Lake — the impound that births this clear, cold current. Myers cranks up his outboard and steers around a slough. Cypress trees hunch along the banks, their knees jagging the shallows. A turtle slides off a log; dragonflies constellate overhead. It's a summer Tuesday, and there's not another person in sight.

These waters produced a world record brown trout once — 40 pounds and 4 ounces, caught by Rip Collins in 1992 — and remains a factory for brown and stocked rainbow trout. The river bottom's rocky moss beds breed insects like caddisflies and blue-winged olives and sowbugs, which feed trout. The trout, in turn, feed people.

The banks of the Little Red are lined with floating docks that range from the ramshackle to the ornate. The fancier roosts have padlocked rod closets, barbecue grills, picnic tables. They carry etched wooden plaques with names like Lloyd's Lodge and Lazy A Trout Dock.

Two dozen such platforms pass, then stillness. Myers points to a blurry smudge perpendicular below the surface, prominent enough to roil the current. There, two feet down, is the line of rocks that armors the Pegasus as it pierces the Little Red River.

"We call it the pipeline shelf," Myers says. "It's good fishing right behind it, where the water comes over and drops off over those rocks and into the deeper pool. Fish just hang out."

Myers figures no one on the river connects this pipeline to the Mayflower spill. Despite the slouching yellow warning signs at the top of the bank, the pipe and the rocks that protect it are, to fishermen, simply another feature to navigate and exploit, akin to a manmade sandbar or boulder.

"I've been over that pipe, pshew, a hundred times," he says. "I had no clue that was the same line as in Mayflower. And it could have easily been here instead of there. Why Mayflower instead of right in the middle of the Little Red?

"One rupture, one leak, one bad episode in a pipeline history, it could devastate our fishing industry."

White County

"We always plan for worst-case scenarios," Tamara Jenkins says on the phone. She coordinates the Arkansas Department of Emergency Response in White County, and once every two years, her crews and Exxon conduct drills that suppose the unthinkable.

If the pipeline were to break in the Little Red River, three things would happen immediately. Searcy, a town of 23,000 people 23 miles away, would shut off the intake valve that slurps drinking water from the Little Red. First responders would lace absorbent booms across the river to corral the oil. The Army Corps of Engineers would stanch the river at its source, by closing the hydroelectric dam at the base of Greers Ferry Lake.

The severed river would continue to spill across the pipe for at least half a day. "It's like trying to stop a train on a dime," Jenkins says.

Counties have reciprocal agreements to help one another in times of crisis. White borders Faulkner County, home to Mayflower. The drive from the Little Red's intersection with the Pegasus to Conway, Faulkner's county seat, is a winding ride beneath bursts of forest canopy, through rolling pastures. The highway passes natural gas pads, an honor-system $6 watermelon stand, the Cleburne County livestock auction barn, a long-gone gas station, now just a bare slab and a sign for $1.39 unleaded. From there it's just a few miles of asphalt to the largest Arkansas city the Pegasus crosses.

Conway: Milepost 322

Megan Brown picked up her road map at the Chamber of Commerce. If you need your own, she says, just walk in and say you're looking to buy a home in town. They'll give you one for free. She modified hers with a black marker, on the lower right corner: the cameo appearance the Pegasus makes in this college town of 52,000.

"I wanted to know where it was, because I live here," the young mother says. "If it spills and a mile away the kids are sick, I want to know, where is it?" Lately she's been thinking about what would happen if the Pegasus — fallow for five months and counting, gunked up with stale sludge — re-opened. If they flip the switch, could the pressure build in Conway, so near the rupture site?

(We ran this scenario past Richard Kuprewicz, a pipeline expert in Washington state, and he said the chance of a blowout during a restart is remote. "It'll mix pretty quick again," he said. "They could run a cleaning pig [pipeline robot] to help get the thing moving if it started to tar out.")

When Brown asked Pegasus-related questions around Conway, she didn't get far. She says she called her city councilmember Mary Smith, who according to Brown said the pipe doesn't go through Conway and suggested she should direct her questions to Faulkner County Judge Allen Dodson, who has led the Unified Command that responded to the spill. "I was like, 'Aw, man. Really?' " Brown says.

Brown's an environmental geology student at the University of Arkansas at Little Rock, and her view of her surroundings is decidedly topographical, rather than political. The PHMSA maps put the lie to the reassuring notion that the Pegasus doesn't cut through town: The pipeline runs through Conway proper, full of places where another break would become its own unique species of calamity.

On Amity Road, the Pegasus runs beneath a Halliburton-owned outfit called Multi-Chem, all vats and big trucks and metal staircases. Everything considered, this might be the most convenient spot for a Conway spill.

At the southeast edge of town, near the north tip of Lake Conway, the Pegasus goes within an eyelash of Caney Creek, a feeder for the fishing lake. Then it burrows under the yard behind the True Holiness Family Life Center, a boxy, metal-sided church.

In the adjacent neighborhood, it runs under a little berry farm where you can pick your own and where silver ribbons on strings flutter to deter birds. It runs under an above-ground pool in a backyard and near a yard that's full of alpacas. Then, onward, just outside town.

The pipe goes under a neighborhood on Skunk Hollow Road, just beyond the city limits, and cuts beneath the backyard of the Little Dumplings daycare. On a recent Friday afternoon, the front yard was full of dumplings scampering around plastic playsets. Everything considered, this might be the least convenient spot for a Conway spill.

"I hear, 'Well what can I do about it?'" Brown says. " 'Is there a petition, can I sign a petition?' Even from people who are uncertain about what really happened in Mayflower, even those people say, 'Don't turn it back on.' "

Tomorrow: On to Mayflower, where Ryan Senia surveys what was once his back yard.

This story is part of a joint investigative project by InsideClimate News and the Arkansas Times. Funding for the project comes from readers who donated to an ioby.org crowdfunding campaign that raised nearly $27,000 and from the Fund for Investigative Journalism.