If you happened to stroll the blocked-off streets downtown and around U-M’s central campus on Tuesday — just before the four-day, 2010 Ann Arbor Art Fairs began — you kind of felt like a guest arriving at a big party five hours early.

Al Sievers of Batavia, Ill., cleans off his abstract stained glass art in his booth on Liberty Street Wednesday morning. Sievers is in the State Street Area Art Fair.

Lon Horwedel | AnnArbor.com

For white-tent-lined spaces that you knew would soon be jam-packed with humanity were sparsely populated; preparations (among artists, food vendors, and retailers) had the strange feel of being both calm and slightly frenzied at the same time; and everybody seemed to function in his/her own world, not yet compelled to look too far outward.

Until the Fairs’ hundreds of thousands of visitors started arriving this morning, that is. At 10 a.m. today, things got under way with blue skies, warming temperatures and crowds of fairgoers all on hand.

But on Tuesday afternoon, artists in various states of preparedness — from just breaking out the tent frame to putting the finishing touches on their presentations — took occasional breaks to reunite with friends (overheard greeting: “How are you bums doin’?”) and beat the uncomfortable, but could-be-worse, heat.

To aid in this effort, three female, sophomore members of Pioneer High’s crew team — Summer Art Fair volunteers — carted a cooler up and down Main Street with bottled water for those who were working, and demand was high.

“You’re giving the water to the young, good-looking guys,” a man teased when they ran out, “not old bald guys like me.” The man took off his hat and pointed at his head.

“You caught us,” one of the young women replied with a sheepish smile.

On Liberty Street, State Street Area Art Fair glass artist Rollin Karg and his wife were in the last stages of preparing Karg’s booth by 2:30 p.m. on Tuesday.

For those who do travel to several fairs each year, the process becomes routine. “We can set up in two hours,” said Karg, who’s brought his art to Ann Arbor for more than 10 years. “But if we’ve got four, we’ll take four. … We took a long lunch, and we’ve been visiting friends” — including fellow State Street artist Robert Trisko, who made the couple’s wedding rings.

Scott Coulter, of Florida, unloads an oversized painting from his trailer as he sets up his booth at the Ann Arbor Street Art Fair on Tuesday afternoon.

Melanie Maxwell | AnnArbor.com

So many artists who are regulars at the Fairs develop friendships with each other. But the Street Art Fair had at least one new face.

Mixed media artist Joan Rasmussen, from Atlanta, said, “This is the show to do. … (The Street Art Fair) just has a reputation amongst artists, and high rankings in the trade. … It really draws art lovers.”

Despite not getting much sleep in the previous 24 hours, her set-up, which began at 11 a.m., had gone smoothly. “It’d be nice if the streets could be widened,” she said. “But I was originally a New Yorker, so I’m used to it.”

Rasmussen also seemed unfazed by the heat — perhaps not surprisingly, given her current residence in Georgia. But one item appeared in or around nearly every booth and its accompanying pile of storage bins: fans.

Box fans seemed far and away the most popular choice — in one instance, there were eight of them lined up at a single booth — though I did spot one artist hooking up a tiny white ceiling fan just above the chair in his tent. Regulars know only too well that sweltering heat, along with the occasional storm, often go hand-in-hand with the Ann Arbor Art Fairs.

Potter Pam Hammes, of Gowen, unloads boxes into her booth on Main Street for the Ann Arbor Summer Art Fair on Tuesday afternoon.

Melanie Maxwell | AnnArbor.com

That fact by itself isn’t likely to dampen the spirits of first-time exhibitors; but unexpected logistical hiccups can make set-up day a little too exciting.

A group of local ceramists, featured in the South University Art Fair, stood around their large tent Tuesday afternoon and debated about the most advantageous layout for the work, and where the cashier’s table should go. The group’s set-up had already been delayed by the need to shorten the tent’s poles by two inches.

“The roof wasn’t taut,” said first-time exhibitor Marilyn Pearce Edington, “And if a storm comes, which it will … “

But such stresses are part of any big event. Everyone — even the young employee stacking flip-flops on a sidewalk sale table — was working simultaneously toward making the Art Fairs a success for artists and local business owners. You could practically hear the hum of industry.

Or was that the hum of cyclists gleefully riding on the median of traffic-free downtown streets for one day?

Could’ve been both, I suppose.

Jenn McKee is the entertainment digital journalist for AnnArbor.com. Reach her at jennmckee@annarbor.com or 734-623-2546, and follow her on Twitter @jennmckee.