Bloomington officials are waiting to see whether a vote by an international group in Paris on Wednesday will go their way, awarding the west metro city the 2027 Expo.

The bid has been a central project in Bloomington for years, and the Legislature has committed millions of dollars to support the event if Bloomington wins.

So what is the Expo, anyway? And why does Minnesota want it so much? Here's what to know.

What is the Expo?

Ever heard of the World's Fair? The international technology and business shows aren't a relic of the 20th century. An intergovernmental body based in Paris called the International Bureau of Expositions, or BIE, still organizes World's Fairs like the most recent one held in Dubai, and smaller Expos that focus on narrower themes. The BIE has 179 member countries.

The Expo that Minnesota wants to host will be a massive trade show focused on health care and the environment. It would run for three months in the summer of 2027. Organizers hope it will draw millions of people and myriad companies from all over the world, on the theme of "Healthy People, Healthy Planet."

The theme is meant to draw attention to Minnesota's health care economy (think: Mayo Clinic, Medtronic, UnitedHealth Group) and the state's abundant natural spaces.

Why does the United States want an Expo here?

"We really view it as a unique opportunity to marry public diplomacy, economic diplomacy and health diplomacy," said the U.S. State Department's Liz Allen, under secretary of state for public diplomacy and public affairs. U.S. officials hope closer ties between people and companies, as well as between governments, will help further U.S. interests, she said.

The Expo could present opportunities for Minnesotan and other American companies to engage with partners and clients from all around the world, Allen said.

The Expo could mean a $4 billion economic impact for the host country, with somewhere between $2 and $2.5 billion of that expected in Minnesota, she said. Organizers have estimated between 7 million and 14 million visitors for the Expo.

Who's behind Minnesota's bid?

The Expo effort has several prominent boosters, including the state's congressional delegation, but the hub of organizing is the bid committee of Expo 2027 Minnesota, USA. Co-chairing the committee are the founder of design-build company Clayco, Bob Clark, and Timberwolves part-owner Marc Lore. John Stanoch is president and CEO of the committee, running the day-to-day.

If Bloomington is chosen to host the Expo, that bid committee would morph into a host committee to organize the Expo and raise money, though the city, state and federal governments will stay involved.

The bid has full-throated support from Bloomington and Minnesota elected officials. Both the Trump and Biden administrations have supported the Expo bid.

Who's paying for this?

The Expo is intended to be a partnership between the public and private sectors, with the largest source of funding meant to be ticket sales and sponsorships. Some of the buildings could be privately developed, likely with local property tax abatements.

Stanoch estimated the whole shebang could cost about $1.4 billion.

The bid committee has raised $2.5 million so far, and the Legislature pledged $5 million to help start planning should Bloomington be chosen.

The Bloomington Port Authority has been planning development in the proposed Expo site near the Mall of America. The port has moved to purchase or has agreements on several parcels around the mall that could be part of the 60-acre Expo campus.

Federal funding will also be in the mix, Allen said, including $50 million to help low- and middle-income countries that want to participate in the Expo.

The last Expo held in the U.S., in 1984 in New Orleans, faced high costs and low attendance and left more than $102 million in debt (about $295 million in today's dollars), some of which was assumed by the state of Louisiana. The U.S. largely disengaged from the BIE after that, and only began to get involved again in the last decade.

Why does Bloomington want the Expo? And why Bloomington?

Minnesota's congressional delegation has been advocating for the Expo for almost a decade. U.S. Sen. Amy Klobuchar said she thinks bringing such a large event to Bloomington isn't such a crazy idea.

"At one point everyone laughed about the Mall of America, and now it's a major tourist attraction," she said. Klobuchar said she hoped a built-in base of mall tourists would help boost Expo attendance and ticket sales.

"This is an economic development program for the city of Bloomington and our region," Stanoch said. "Would you rather have asphalt and weeds or would you rather have jobs and people and doing good?"

Bloomington officials aim to spur development instead of vacant lots and aging hotels around the Mall of America, with the former site of the Thunderbird Motel to be the center of the Expo campus. They hope buildings and infrastructure built for the Expo and paid for in part by the private sector can be repurposed as something more permanent.

Seen in that light, Bloomington's dozens of acres of undeveloped and underdeveloped land are an advantage over other metro cities. The proposed Expo site is also close to the Minneapolis-St. Paul International Airport by car and public transit.

When will we know if Minnesota's bid wins?

Voters gathered in Paris will make their decision by about 7 a.m. Wednesday Minnesota time through a system similar to ranked-choice voting.

If no bid wins a two-thirds majority on the first round, the country with the fewest votes will be eliminated and votes redistributed to voters' second choice, until a country gets to a two-thirds majority. So part of the U.S. advocates' job has been persuading some delegates who are committed to another country to rank the United States second.

"I have been personally calling ambassadors all over the world; we are making a strong strong pitch for Minnesota," Klobuchar said. The State Department is also courting BIE votes, Allen said.

Spain is considered the fiercest competition.

Check startribune.com for updates on Wednesday morning.