On Patriots’ Day, the runners outnumber town residents nearly six to one. Their presence closes the roads and takes over the high school and most open space in the town’s center. Crowds pack the pizza shop and corner drugstore and cover the lawns of the church, the library and the town offices. On Patriots’ Day, a simple billboard, topped with small flags of nearly 80 nations, sums up the scene.

“Welcome to Hopkinton. It all starts here.”

Yesterday marked the 78th time Hopkinton’s West Main Street has served as the starting line for the Boston Marathon. Each year, this town of 2,600 essentially shuts down, allowing its small common to become ground zero for the start of what’s become the second largest single-day sporting event in the world, behind the Super Bowl.

“It’s a wonderful time,” said Hopkinton resident Kathy Taylor. “It gives us a chance to meet new people from all over the world. All around town, the runners really make themselves visible all week long.”

As the sun rose over the common yesterday morning, the shopkeepers, spectators and sprinters dribbled in. Within hours, Hopkinton’s population swelled a dozen times over as the world turned its attention to its most storied modern marathon.

By 10 a.m., the Hopkinton common looked, smelled and sounded like a state fairground. Small town life blended seamlessly with corporate America. Across from the NexTel cellular booth, the town’s Little League sold candy. The Hopkinton High School booster club had a table just a few dozen feet from the Stanley Cup — yes, that Stanley Cup. As a giant walking nose welcomed spectators with free BreatheRight nasal strips, the town Chamber of Commerce welcomed “the runners of the world.”

Despite the Boston Athletic Association setting up an Athletes Village at nearby Hopkinton High School, runners filled the common to stretch, fuel and mentally prepare themselves for the odyssey ahead. Jose Denogean, a 42-year-old from a small town outside of Mexico City, ran six other marathons before deciding this year to make his first attempt at Boston.

“I came here because this is the only marathon that puts the pressure on you with a qualifying time,” Denogean said. “It’s very special in that regard.”

Also making a Boston debut this year was 23-year-old Stephanie Crawford, a Seattle native who moved to Framingham two years ago. Watching from the sidelines last year pushed her to enter October’s Bay State Marathon, the first marathon she ever entered. Now, she was ready to attack Heartbreak Hill.

“Boston was just exciting last year,” Crawford said. “The fact that it’s so old, it’s become a tradition. You hear about the Boston Marathon everywhere.”

“Everybody that’s ever run marathons wants to run in Boston,” said Paul Hill, a two-time Boston participant from Tyler, Texas. “It’s built a reputation for itself over the years, since it’s been run continuously.”

The Saxon family has turned marathoning into a family affair. Husband George and wife Diane have run more than 100 marathons between them. Both natives of nearby Taunton, the couple planned to be joined by their 16-year-old son Christopher at the 16-mile mark.

“[The BAA] does a first-class job. Everything is well organized. I’ve run a lot, and it can be just chaos,” Diane said. “Plus the crowds are awesome, especially on Heartbreak Hill.”

“We’ve done about 30 different marathons, and this one is by far the best,” George Saxon added. “With the race in the afternoon, beverages really get the crowd rolling even better.”

As the clock ticked closer to the Open division’s noon starting time, Hopkinton buzzed. The Korean Presbyterian Church adjacent to the start line offered prayers on its front lawn. A brass band began to play in the gazebo. As the Boy Scouts grilled hot dogs and hamburgers for the eager crowd, runners fought to cope with the pre-race jitters.

“I just get really nervous right before a race,” Crawford said. “All I can do is just sit here in the sun, just watching the people go by to calm down. Just wait, and try not to be too nervous.”

The 54-year-old Hill had a whole different perspective on nerves.

“It’s strange, I really don’t feel like I’m going to do anything. I feel like a spectator until the gun goes off,” Hill said. “Then the adrenaline kicks in, and it’s ‘Hey, you’re in a marathon.’”

At 10 before noon, preparation time ceased. The band stopped and the common cleared, as spectators and runners packed the start area. With news helicopters whirring overhead, the athletes literally threw their warm-ups to the ground, waiting for a lone gunshot to break the tension. When it came, the seemingly endless stream of runners got a last bath of cheers from the Hopkinton crowd as they proceeded down the hill.

In the sea of beanies and bunny glasses, cow suits and balloon hats, everyone had his or her own goals for the marathon. Hill wanted to match his 2000 time of just under three and a half hours. Denogean saw just running the marathon as its own reward. Some ran to “Cure ALS,” another to “do it for Uncle Tony.”

With the leaders nearly five miles into their run, the last runners crossed the start line. As the booths closed, the crowd cleared and the roars faded, Hopkinton returned to its small town roots. It’ll be business as usual there until next Patriots’ Day.

It really does all start there.