History starts Tuesday.

Most know the historic importance of bringing the Olympics to Atlanta, or launching the world's busiest airport or keeping thousands of talented students in Georgia with the HOPE scholarship.

Tuesday's T-SPLOST vote is Atlanta's next historic move.

Advocates for the transportation sales tax referendum call it "an Olympic moment" for the region. They say it's a chance to tackle the traffic congestion that is choking the region's economic and family life.

Opponents call it a potential mistake of historic proportions. They say passing it would erase the chance to think up a better plan.

For the first time, voters across 10 Atlanta counties will vote together, and be taxed, or not, together as a region.

Win or lose, good or bad, Tuesday's vote on a 10-year, 1 percent sales tax that would raise $7.2 billion ($8.5 billion after inflation) for roads and transit projects will drive the region's future.

It could create the biggest single infusion of infrastructure money in the state in generations.

Not many decisions in Atlanta's past carry more weight. Here is how some came to be.

The airport

In the 1920s, an Atlanta official named William Hartsfield — the future mayor — persuaded the city to lease, and then buy, a racetrack for an airport.

There was some controversy, said Harvey Newman, a professor at the Andrew Young School of Policy Studies at Georgia State University. "The city was really tightfisted about investing in anything."

Hartsfield, and later Mayor Maynard Jackson, pushed the city to expand it with runways and terminals, and fought to be chosen for air service and stopovers.

"The transaction to move Delta here and build that airport, and [its continued expansion] were probably the most important economic decisions that were made in Georgia," said Richard Anderson, CEO of Delta Air Lines. "Because if you look back ... we were probably about the same size as Birmingham, Ala. And now Atlanta is the economic center and cultural center of the southeastern U.S."

Hartsfield-Jackson International Airport is the world's busiest. T-SPLOST advocates use it as an example of how Atlanta's history as a transportation hub mandates investment, and repays it many times over.

"If we do not have the infrastructure to be able to recruit other companies here, they're going to end up going to other cities," Anderson said.

Opponents reject the comparison.

"I just don't see how you can have an impact that's even in the same universe with Hartsfield airport," said Bob Ross, a tea party founder who believes mass transit is inefficient.

HOPE scholarship

More than 1 million Georgians voted in 1992 against the lottery that created the HOPE scholarship. They lost.

Once rolling, HOPE kept thousands of high-performing Georgia kids in state, pumping up the educated workforce and improving the quality of state universities.

It lifted Georgia's national reputation. An editorial in The Philadelphia Inquirer wrote HOPE "is the kind of thing you look at half in amazement and half in anger, and wonder why your own bonehead state didn't think of it."

There was a flip side. Addiction counselors have called the lottery a gateway to compulsive gambling for some. And research shows customers are more likely to be lower income. With skyrocketing use, the fund is short of money, and can no longer pay full tuition for most.

Still, in 2010, a U.S. Chamber of Commerce report cited HOPE as one reason the state was poised to create jobs.

The Games

The last time someone ran a $6 million to $8 million campaign to rebuild Atlanta, it was businessmen trying to win the 1996 Olympic Games.

Unlike the T-SPLOST, they were after something unprecedented. It drew the world's attention. It was prestigious.

But it wouldn't have passed as a referendum, said Andrew Young, who worked to win the Games as Atlanta's mayor. People were still spooked by the debt Montreal incurred for its 1976 Games.

"They clearly would have voted it down," Young said. The plan easily passed the Legislature, he said, because the Atlanta Games backers promised to make a profit. "Now we could do that with transportation if people wanted to pay toll rates. Everybody going to the Olympics had to buy a ticket. You pay for everything you get."

Elected officials made the big commitments for the Olympics in a state of eager enchantment, before the Games were awarded.

When reality struck and Atlanta won the Games, it was too late to quibble.

Some felt left out, as revitalization skipped neighborhoods, or faded away after the Games concluded. Others felt the commercialization set a bad precedent.

No one disputes that the Games changed Atlanta, bringing it instant status as a global city, not to mention sports venues, dorms and parks. Estimates clocked the overall impact to the economy at $5 billion.

And all that growth had a side effect: more traffic.

Staff writer Laura Diamond contributed to this article.