Both camps are fueled by older, working-class whites spurred by nationalism and nostalgia for a bygone era. Their economic prospects have diminished in an era of globalization, and they feel that immigration is damaging their pocketbooks and their cultural identity. And they think the elites aren't listening.
"They're frighteningly close," said Mary Nugent, a doctoral candidate who teaches U.K. politics at Rutgers University. "The demographic breakdown is also similar in that overwhelmingly lower-educated and lower-income people voted for Brexit. That's true of Trump supporters as well. It's an expression of disaffected, mostly white voters and an expression of the feeling of not being heard."
Their slogans evoke the same sense of nostalgia. Trump would "Make America Great Again." The Leave campaign vowed to "Take Back Control."
"They look back on a past where they were an economically significant part of the economy," Nugent said. "Pittsburgh has a lot of nostalgia for its former role in making steel. That's similar to Sunderland and its shipbuilding community."
In other words, if Trump could win Allegheny County the way Leave won Sunderland—or the precincts around Dayton, Ohio, or Milwaukee, Wisconsin—he would go a long way toward putting those swing states in his column, and that's a formula for getting to the White House.
"Many companies have left this area," Trump said at a June 11 rally in Pittsburgh. "You got wiped out. Your manufacturing is way down, your steel is way down." He made stops in Dayton and Milwaukee to make similar arguments against foreign trade pacts and by promising to restrict immigration, build a wall on the border with Mexico and ban Muslims from entering the U.S.
In Scotland Friday to look over a golf course he owns there, Trump, who had endorsed the pro-Brexit forces, praised the resolution and argued that there are "great similarities between what happened here and my campaign." Sporting a "Make America Great Again" hat, he added, "People want to take their country back."
Yet the faster pace of demographic transformation in U.S. makes Trump's task of assembling a winning majority more difficult than the Leave campaign's road to victory. The American electorate of more ethnically diverse voters, along with the state-by-state nature of the U.S. presidential election, give his opponent, Hillary Clinton, a major advantage—and are factors not mirrored in the Leave referendum. A recent Bloomberg Politics poll gave Clinton a national lead of 12 points.
Still, a rising tide of populism and distrust of political elites in the U.S., similar to that which fueled Brexit, gave even Clinton a scare in her Democratic primary, where democratic-socialist insurgent Bernie Sanders won millions of vote and exceeded expectations.
The Brexit vote "is a criticism of the entire global establishment," said Mauro Guillen, who teaches international relations at University of Pennsylvania. "The U.S. election has been a manifestation of this. Voters are so upset by what’s going on, and they’re willing to accept solutions that don’t make any sense."
Like the U.S., the UK has struggled to regain robust growth following the 2008 global financial crisis. In 2015, the UK economy expanded 2.3 percent and is projected to grow at a 1.8 percent rate this year, according to a Bloomberg survey of economists. The U.S. economy expanded 2.4 percent in 2015 and that's forecast to slow to 1.9 percent this year. In both countries, wage growth has been largely flat.
The Organization for Economic Cooperation and Development estimated before the vote that by leaving the 28-nation EU, U.K. economic growth could be lower by 0.5 percentage point in 2017 and 2018 and by 1.5 percentage points in 2019.
Elites Caught Off-Guard
The confidence that many of Britain's senior politicians and its affluent, more highly educated citizens had regarding Brexit's likely failure mirrors the certitude that many American political luminaries had that Trump's campaign for the Republican nomination would fail. U.K. Prime Minister David Cameron staked his standing on the rejection of Brexit, and on Friday he announced his resignation. "There was a complacency among political elites that this could never happen," Nugent said.
Whether or not Trump can pull off a similar feat in the U.S., the stunning Brexit vote carried an important lesson for Trump's opponents: nationalist sentiments that tend to be invisible to elites on both sides of the pond are being activated swiftly, and to great effect.
In the wake of the vote, global stocks tumbled and the British pound dropped to the lowest in more than 30 years, a market rout with echoes of the financial crisis. Former U.S.Treasury Secretary Larry Summers wrote in the Washington Post on Friday that the odds of a U.S. recession within the next year are "now in the 30 percent range.''
An economic downturn, even if connected to the Brexit vote, would likely hurt Clinton as a member of the party in power. Her policy adviser Jake Sullivan on Friday said the turmoil caused by the U.K.'s exit from the European Union would instead bring votes to her side in the November election.
Richard Haas, president of the Council on Foreign Relations, called the Brexit vote "a warning" for Clinton because the social and political forces that drove the outcome are close to those propelling Trump. "The next four and a half months in the U.S.," Haas said, "are going to be informed by the perceived lessons coming out of the Brexit vote."
—With assistance from Jennifer Epstein and Bill Faries.