They are becoming a staple of weekends between June and September, taking their place alongside bathing suits, vacations, and flip-flops.
Trunk parties are hot.
The soirees named for a piece of luggage once synonymous with packing for college symbolize the rite of passage from high school to college.
For party planner Shauntae Doughty, who has organized 10 of the summertime affairs, "it's all the rage."
Perhaps nowhere is that more evident than on the Internet, where college-bound students invite friends to them, post pictures of them, and register at stores for them.
"Sometimes, it's the last time you'll see your friends," said Temple University-bound Olu'Rotimi Solanke, 18, of Philadelphia, who had a trunk party on Aug. 11. "And it's a way for family and friends to help out, because college is a lot of money."
The parties are goodbye gatherings to which guests bring gifts - anything from towels, irons, shower caddies, desk lamps, toilet paper, and notebooks to bedding, mini-refrigerators, and laptops - to help students make the transition from home to college.
The largesse is often placed in a trunk displayed prominently during the parties.
Bed, Bath & Beyond has had an increasing number of teens using its college gift registry for trunk parties, spokeswoman Jessica Joyce said.
The gatherings can be small affairs such as Amber Dwight's afternoon party at a church in West Philadelphia or a big 100-guest celebration like Amber Connally's Hawaiian-themed party at the Ridgway Pool in South Philadelphia.
Sometimes, it's having friends and family to the house, such as the get-together for Cabrini College-bound Briyanna Purnell or the party for Steven Wiley-Curtis at the Arts Garage.
The Fairmount performance venue hosted nine parties this summer and had to turn away requests for 11 others.
The origins of the events are unclear. Sally Rubenstone, senior adviser to the school admissions website College Confidential, said she first heard of a trunk party 40 years ago from a southern classmate while a student at Smith College in Northampton, Mass.
Between then and now, the parties seemed to fall out of favor, but they have reemerged with a vengeance, said Rubenstone, who is also a college counselor. Longtime wedding planner Vikki Leach of Lansdowne attributed the surge to the struggling economy combined with the exorbitant cost of a college education.
Family and friends who gather to celebrate and help buy dorm-ready gifts are "a part of the concept that it takes a village," Leach said. "This is the village wrapping their arms around the student as they go away from home."
Doughty, co-owner of Center Stage Party Planning in Philadelphia, sees the trend as an extension of the emphasis on entertaining that has been the focus of TV shows about weddings and "super Sweet 16s."
But for Rubenstone, the resurgence may be the product of a generation of parents who habitually reward their children for even the smallest accomplishments, so "of course, the whole community will mark" their departure for college.
Some postings on the College Confidential site describe the practice as a "tacky" way to get gifts for college.
Rubenstone understands that view among communities or families where going to college - or going to the snazziest colleges - is routine, and if students have had a graduation party.
But that argument doesn't apply to students who perhaps are the first in their families to attend college, or for whom college is a big deal in the family and community, Rubenstone said.
Davondra Turnell, who will study physical therapy at Manor College, broke down and cried at her party last month when each guest stood and offered words of encouragement.
"It was a reality-type thing," Turnell, 18, of North Philadelphia, said. "Wow, I'm really leaving. I don't want to leave, but I know it's the next step in life."
Daniel and Terri Mack of Sharon Hill said they got no complaints from guests invited to daughter Teyonna's party on Sunday. Everyone was told gifts were optional.
"This is about celebrating her moving on to a new chapter," Terri Mack said.
For Leslie Torres, who raised two children as a single mother, the gifts are a much-appreciated bonus to a crowning achievement. Her daughter Imani Fortune is going off to college.
On Sunday, a card table at Torres' home was overrun with gifts including a mirror, desk lamp, calculator, Band-Aids, toilet paper, and school supplies.
Fortune said the party was about more than the gifts.
"It's really about seeing family and friends," she said.
While guests dined hot dogs and hamburgers, Torres scurried around the house, a harried but happy hostess.
"It's been a struggle to get to this point," she said. "For someone to care enough to come and to give means so much."