What a difference 100 years makes.

The Detroit auto show sponsored by local auto dealers began in 1907 as little more than a dealer showcase of 100 vehicles in a ballroom on Jefferson Avenue. About 6,000 people attended.

A century later, the North American International Auto Show is a global event that pumps $500 million into the local economy, attracts 6,500 journalists and more than 800,000 attendees as well as celebrities and auto execs from around the world, and brings exposure to a city that often struggles with its gritty image.

Over the years, the Detroit show has become the Super Bowl of the auto industry. It's not only an important vehicle for automakers to roll out new models and dealers to drum up traffic.

It also gives everyday Joes and Janes a chance to see the best the world's biggest automakers have to offer under one roof at Cobo Center.

Farmington Hills resident Wendy Herndon said the show is the ultimate in one-stop shopping. Since moving here from Toronto three years ago, she, her husband and their kids have attended it annually.

"Instead of going from dealership to dealership, I can just come to the auto show and see all of the cars," said Herndon, a freelance public-relations specialist who is looking to buy a fuel-efficient luxury vehicle.

For Kewsi Mann, a 35-year-old Detroit resident, the show is a family ritual. Mann, a photographer who remembers going every year as a boy, now takes his four children, ages 14 months to 13 years, to the auto show.

"It's nice to know what things are coming out in the future and what sets trends," he said. "Looking at a concept car is like looking at a spaceship."

That type of sentiment is part of what's driven growth of the Detroit show, which took several years off during World War II. The show, which became an international event in 1989, now displays more than 700 vehicles — a sevenfold increase from its first year.

In fact, the show's continued growth is so important that plans for expansion of the 700,000-square-foot Cobo are pegged to the need for the Detroit show to remain a premier event, as well as to attract other conventions.

"The show has become the center of the universe for all the major players in the automotive industry around the world to converge," said Doug Fox, vice president of the Detroit Auto Dealers Association, which runs the event. "Now, we have to really think forward about what we're going to do over the next 100 years."

For some dealers, the event's continued expansion is key. Martin "Hoot" McInerney, who owns Star Lincoln-Mercury in Southfield, Mich., said the show almost immediately translates into increased traffic on showroom floors.

"It's tremendous for us," said McInerney, who has been in the industry for more than half a century. "We could never market a car like they do or spend the millions of dollars on displays."

For automakers, the show has become a chance to unveil new vehicles and technologies on an international stage. According to the Detroit auto dealers group, the majority of new vehicle introductions at U.S. auto shows takes place at the Detroit show.

Automakers say that takes months of planning. "Before it was 'borrow a car from dealers and put it on display,' but now it's a more elaborate affair, a more enjoyable experience," said Phil Bockhorn, senior manager for global auto shows for DaimlerChrysler AG's Chrysler Group, which will have 91 vehicles on display during this year's show.

The Detroit show has also become important to the region. In addition to the $500 million windfall to the area each year, the event also is used as a way to boost Detroit's tattered image. After all, it draws journalists from more than 70 countries each year.

"There are thousands from the media writing stories about the region, and if we can help them feel better about Detroit, we will," said Richard Blouse, president and chief executive officer of the Detroit Regional Chamber. "I just always pray we don't have 30 inches of snow."