MEXICO CITY — The subtext was hard to miss.
On Wednesday morning, soon after the announcement that the United States, Mexico and Canada had won the vote to be joint hosts of the 2026 World Cup, President Enrique Peña Nieto posted a video on Twitter celebrating the news.
Standing in front of the presidential residence, Los Pinos, he pointed out that Mexico would become the first country to host three World Cups. He extolled the virtues of Mexico as a tourist destination, including its beaches, archaeological sites and “hospitable and warm people.”
And he zeroed in on a concept that has been evasive of late in the bilateral relationship with the United States.
“We’re deeply unified,” he said, of the three host countries. “Congratulations for being hosts together.” He emphasized the word “together” by clenching his fist.
Mr. Peña Nieto made no mention of President Trump. But the American president could not have been far from his mind.
These have been trying times for the relationship between Mexico and the United States, and the World Cup, a magnificently complicated undertaking, would seem to impose an additional test.
Beginning even before his election in 2016, Mr. Trump has taken an openly hostile stance toward Mexico on various issues, from migration to trade to security, jeopardizing the hard-fought diplomatic symbiosis that generations of officials on both sides of the border have built.
Last month, as the sides were struggling to rewrite the North American Free Trade Agreement, Mr. Trump announced tariffs on steel and aluminum against Mexico and Canada, which drew retaliatory Mexican levies on a range of American goods.
But the news of the World Cup winning bid — dubbed United 2026 — was celebrated throughout Mexico, a nation deeply passionate about soccer.
Arturo Sarukhán, a former Mexican ambassador to the United States who has for several years championed the idea of a World Cup with the two countries as joint hosts, hailed the event as a chance for repair.
“A unique opportunity to create people to people connections & heal some of the wounds in the narrative of ‘us vs them’ being propelled by Potus,” he said on Twitter.
The tournament won’t come to North America for another eight years, so even if Mr. Trump were re-elected for a second term, he would be long gone from the White House by the time of the opening kickoff. But planning for the event has already begun.
It’s a herculean undertaking that will require fine-tuned diplomacy between the host nations, and lots of cooperation between organizers and myriad federal, state and local agencies in all three host countries.
But it is also expected to be a largely private-sector endeavor, and as long as politicians keep their politics out of the way, experts say, things should go smoothly.
Mexico and Canada will each hold just 10 of the 80 matches, compared with 60 in the United States, which also will be the site of the quarterfinals, semifinals and final.
The only other time FIFA awarded a World Cup to more than one country was in 2002, when Japan and South Korea were hosts of the tournament. But keeping the peace between those contentious neighbors proved so difficult that FIFA vowed never to do it again, Jeffrey Webb, a former executive committee member, told The New York Times in 2015.
FIFA’s decision to expand the tournament to 48 teams from its current 32, however, almost immediately put co-hosting back on the table. The sheer scale of the expanded format seemed to demand it: The tournament’s 80 games in 16 stadiums involve more than 1,100 players.
The winning bid promised to sell 5.8 million tickets, a total that dwarfs the existing record of 3.6 million.
The United States and Mexico know a thing or two about working together on complex business deals. Under Nafta, regional trade exceeded $1.1 trillion in 2016, and United States foreign direct investment stock in Mexico climbed above $100 billion, according to the Council on Foreign Relations in New York.
The countries are also deeply intertwined through migration, culture, language, history, natural resources and — yes — sports.
“These are the two most integrated large countries on the planet,” said Agustín Barrios Gómez, a former Mexican congressman and the coordinator of the working group on United States-Mexican relations for the Mexican Council on Foreign Relations in Mexico City.
“No other country has as much of an impact on the daily life of the United States as Mexico, and vice versa,” he said.
Andrew Selee, president of the Migration Policy Institute and author of “Vanishing Frontiers,” about the deeply intertwined relationship between the countries, said the current tension between the Trump administration and its counterparts in Mexico and Canada was “a short-term reality.”
“The longer term is about deeper integration,” he continued, “and the World Cup is a fitting symbol of that.”
Andrew Das contributed reporting from Moscow