There were four on Wednesday. There will be 12 today. And 57 on Friday.
They're pouring into Raccoon Mountain Caverns and Campgrounds to mark Memorial Day weekend with open fires, hot dogs and lawn chairs.
"We're booked up for this weekend on the campground Friday, Saturday and Sunday," said park manager Eric Bosley. "It's really good."
Bosley isn't the only business owner bracing for a spectacularly busy Memorial Day weekend.
Holiday travel is expected to soar to prerecession highs this weekend across the nation, with 36.1 million people taking a trip more than 50 miles from home between Thursday and Monday, according to the American Automobile Association. That's the most travelers since 2005, and a 1.5 percent increase over last year's 35.5 million travelers.
The rise is driven by increased confidence in the economy, lower gas prices and pent-up demand after this year's harsh winter, said Don Lindsey, AAA Tennessee public affairs director.
In Chattanooga, about 25,000 people are expected to line the streets for the USA Cycling Professional Road and Time Trial National Championships on Monday, and downtown hotels were already filling up early this week -- most between 75 and 100 percent booked by Tuesday.
The summer push could help boost Chattanooga's hotel market, which faltered in 2013 with dropping occupancies, demand and rooms sold.
This year already is looking better, according to data released Monday by industry expert Smith Travel Research. While Chattanooga hotel occupancies were still down 2 percent in April, demand grew -- the city sold 191,000 hotel rooms in April 2014, a solid improvement over April 2013's 186,000 rooms sold.
"Things are looking up," said Bill Mish, general manager of the DoubleTree by Hilton. "We're excited. There's been years when I haven't been 100 percent convinced going in, but looking at the different market segments, they all seem to be pretty darn strong."
Memorial Day weekend is the unofficial start to summer and a barometer for the rest of the tourism season, said Bob Doak, president and CEO of the Chattanooga Convention and Visitors Bureau. So a strong Memorial Day bodes well for the coming months.
"All indicators are that everything is ahead of this time last year," Doak said. "Sometimes I say I'm 'cautiously optimistic,' but this year I'm not. We're optimistic."
A couple of longstanding festivals will celebrate key anniversaries this summer -- the Southern Brewers Festival turns 20 and rowing regatta Head of the Hooch marks 10 years. And the city has added new attractions as well, like the revamped otters exhibit at the Tennessee Aquarium and High Point Climbing and Fitness in The Block in the old Bijou Theatre on Broad Street.
The Ironman triathlon will debut in Chattanooga in September, as will the American Quilter's Society's QuiltWeek. Together, the two new events -- which should generate a combined $70 million in economic activity over the next five years -- lengthen Chattanooga's tourism season, Mish said.
"It used to be summer season ended with the kids going back to school in August, but it's really extended into September this year," he said. "That should blow the numbers right away."
Adding new events and even brick-and-mortar attractions will be critical to Chattanooga's future growth, Doak said, even beyond this summer.
Tourists, he said, like new.
In fact, the aquarium's new offerings are what finally convinced Etowah, Tenn., resident Mary Green to bring her granddaughter to downtown Chattanooga.
"I've lived here for 14 years and never been down here," she said. "But I always see on the news that they're adding new attractions."
Back at Raccoon Mountain Caverns and Campground, Bosley said he's 70 percent booked for the entire Riverbend festival, will sell out on the Fourth of July and has already booked a few spots in September for Ironman. But he's still cautious.
"Summer will be good," he said. "As long as the weather is good."
Contact staff writer Shelly Bradbury at 423-757-6525 or email@example.com with tips or story ideas.