The road to the White House leads from the life-size cow carved from 600 pounds of butter here at the Iowa State Fair to the stand selling $7 grilled pork chops on a stick.

There’s where Hillary Rodham Clinton was strolling on Saturday, shaking hands and posing for selfies with sweaty supporters under an unforgiving sun, when the whirring sound of helicopter blades approached, then grew louder, then louder still.

“Look up in the sky!” Greta Tarbell, 63, cried out. “There’s Trump! He’s got his own helicopter. Have at it, baby!”

The black chopper with bold white letters spelling T-R-U-M-P circled the fairgrounds once. Then twice. Then a third time.

The Donald had arrived. And with that, the forces that are making the 2016 presidential contest so extraordinary collided theatrically at the legendary Iowa State Fair.

Arriving by helicopter on Saturday, GOP presidential candidate Donald Trump was cheered on by hundreds of supporters as he toured around the Iowa State Fair and chaos ensued. (Alice Li/The Washington Post)

Donald Trump, the billionaire reality television star whose shamelessness and braggadocio is disrupting the Republican primary, was out of his element here but undoubtedly in command.

He stepped out of his helicopter like a Palm Beach mogul, sporting a navy blazer and breezy cream slacks, a red cap with his “Make America Great Again” slogan, French cuffs and buffed white dress shoes, which would be challenged moments later when the Trump entourage walked through a pile of horse dung.

A political Willy Wonka, Trump offered rides in his helicopter, which landed at a nearby baseball field, to randomly selected handfuls of Iowa children. “Come here,” he said to the kids. “Does anyone want to take a ride? It’s nice, right? . . . Who wants to go first?”

“You know we don’t do subtle,” Trump’s spokeswoman, Hope Hicks, acknowledged.

This, apparently, is how America chooses its presidents.

At the fairgrounds, there was no collision between the Democratic and Republican front-runners. Still, the chaos and spectacle Clinton and Trump each created during their visits Saturday crystallized the dynamics of the race.

First was Clinton. A dynasty candidate criticized for being aloof, she tried to ingratiate herself with everyday Iowans. She had as her guide Tom Harkin, the state’s legendary populist senator who retired earlier this year and gave Clinton his endorsement on Friday. Harkin, wearing his signature straw hat, showed her the way.

The former secretary of state stood at the fence of a dirty paddock to meet a shorthorn cow named Maggie. (She paid no attention to the shiny black Rolls-Royce parked a few yards away.) She expressed amazement at a Monopoly-themed butter statue. She bit into a greasy pork chop and sipped from a jumbo cup of fresh-squeezed lemonade.

“I love your blue outfit!” Clinton gushed to one stranger.

“This is like being back at the New York State Fair, surrounded by friends,” she told another.

Walking through the Agriculture Building — past showcases of the thickest carrots, roundest beets and biggest heads of iceberg lettuce — Clinton made her way to the famed butter cow. She smiled and waved, waved and smiled.

“I’m so excited,” said Kate Reed, 48, an accountant. “This was my whole goal today, to get to see her. But oh, my God. This is insane.”

From start to finish, Clinton was surrounded by a swarm of Secret Service agents, campaign staffers and reporters shouting questions such as, “What about your e-mail servers?” and “Have you had any conversations with Biden?” (The vice president has been weighing whether to challenge her in the Democratic primary.)

The everyday Iowans Clinton had come here to meet and win over risked physical danger getting close to her. The candidate was engulfed by a mob of media and photo-snapping supporters, everyone hot and sticky, tripping over each other.

“Is that her behind the bald guy?” one woman asked. “I’ve seen blond hair pop up a couple of times.”

Louis Picone, 44, got close enough. Then he taunted everyone else. “I shook Hillary’s hand,” he called out. “Only $2 to shake my hand!”

And that was before Trump showed up.

An even larger horde surrounded the celebrity businessman as he inched down the main concourse of the fair, past picnic areas and stands hawking such heart-healthy delicacies as deep-fried nacho balls, bacon-wrapped smokies on a stick and deep-fried Twinkies.

“I have a crowd 10 times what Hillary had,” Trump boasted, though his estimate was definitely inflated. Earlier, reminding reporters he topped the latest polls here, Trump declared: “I love Iowa, great place. I’ve really developed a relationship with it.”

“Hey, Donald, you’re my favorite man!” shouted a boy, who stood on top of a golf cart to see the candidate in the red cap walk by.

The scene was mayhem. Trump’s private security agents tried to enforce a buffer around him. When a camera crew dropped a boom microphone overhead, an agent said, “Gotta keep the mics away from his head.”

Fans reached out their arms toward Trump. They stood on their tiptoes to snap pictures of the man they recognized from television. They screamed his name and cheered him on. “Give me a selfie!” yelled one fan. “Save our country!” screamed another.

After one woman shook Trump’s hand, her friend gleefully asked, “Was his hand soft?” She said it was.

Al Linquist, 63, called his wife from the middle of the scrum: “I just shook hands with Trump. Honest to God. Scouts’ oath. I got my hand in there and told him, ‘Keep it up!’”

But not everyone gawking at Trump was so encouraging of his campaign.

One woman stood on a park bench and shouted, “Donald, we love you! Woooo!” But when a reporter asked if she really loved him, she shook her head sheepishly and said, “No, do you?”

Faith Lain, 37, was absolutely giddy after meeting Trump, but he doesn’t have her vote.

“He’s a spectacle and he’s ridiculous,” she said. “That’s why I wanted to shake his hand. . . . The state fair is about doing ridiculous things. And there’s nothing more ridiculous than Donald Trump being president.”

When Trump got to the pork chop stand, where Clinton had been only an hour earlier, an aide handed him a box of chops on sticks. He picked up one, took a big bite out of it and held it up for the cameras. “This is the real deal, right?” Trump said. After one bite, however, he put the chop back in the box. He didn’t eat anything else.

Trump, who earlier in the day had singled out former Florida governor Jeb Bush for criticism, called out to the crowd that had gathered: “Who do you support? Trump or Bush?”

“Trump!” the crowd yelled back. The candidate mugged for the cameras and held up two fingers in a victory sign.

Both Trump and Clinton opted out of appearing at the Des Moines Register Soapbox, a state fair rite of passage for presidential aspirants, who each get 20 minutes to address fairgoers — and often get mercilessly heckled. Trump said he skipped the soapbox because of his feud with the Register. The newspaper, he said Saturday, was “not relevant.”

Some of Clinton’s supporters criticized her decision to avoid taking questions from fairgoers at the soapbox, although she did answer a few questions from reporters at a morning news conference.

“She should go to the soapbox, absolutely,” said Nancy Thise, 47, a Clinton supporter. “She should get it over with. She should face her fears and her critics. People love her for the right reasons and her campaign people are not doing her any justice by protecting her.”

Shortly after Clinton and Trump were ferried off the fairgrounds — Clinton by armored Chevrolet Suburban, Trump by golf cart — Sen. Bernie Sanders (I-Vt.), who is waging a populist challenge to Clinton for the Democratic nomination, stepped onto the soapbox.

As Sanders’s commanding voice boomed from the tiny stage, hundreds of people — perhaps 1,000 or more — stopped in their tracks to listen, making the main concourse of the fair nearly impossible to pass for the roughly 15 minutes he spent speaking.

Sanders delivered his talking points about leading a “political revolution” to take on “the billionaire class.” And then, up in the sky, he spotted Trump’s helicopter hovering, soon to leave town.

“I apologize,” Sanders told the crowd. “We left the helicopter at home.”

Philip Bump contributed to this report.