This is the time of the great annual American migration, when millions of restless young people range across the country, bearing great dreams for the future -- and way too much stuff.

If you're packing up the car today, you know what we're talking about. The kids are going off to college, many of them for the first time. No one knows exactly how many are out there at this moment, but the numbers suggest that it's best to get out of the way: The United States has more than 4,000 colleges and universities, with 2 million students living in college dorms. Throw in the many returning students who live off-campus, and there may be as many as 4 million (along with a few million parents) on the road from mid-August until mid-September. "It feels like the whole world is showing up at once," says Eddie Hull, who knows all too well what he is talking about. He is dean of residence life and executive director of housing services at Duke University, as well as president of what might be called one of the world's largest landlord organizations -- the Association of College and University Housing Officers International.

You can tell he's already moved his students in. "My face still hurts," he says. That would be from all the smiling he's been doing as he greets his tenants.

Those millions of students generate many numbers. Here are a few of them:

* 17,200. That's the capacity of the largest residence hall system in the country, located at Michigan State University in East Lansing. But that's not even the largest number on the MSU campus. Try this: Last year, the university's students consumed, among other things, 2.7 tons of hummus, 157 tons of cheese, 5,933 pounds of Cinnamon Toast Crunch cereal, 402 tons of chicken (from fingers to breasts), 60 tons of beef, 43.4 tons of hamburgers, 2.5 million eggs and 57.8 tons of bananas, says Bruce Haskell, the university's food services coordinator. They drank 54,690 gallons of blue Mountain Blast Powerade, which edged out Coke Classic for the first time. "It's a great report," Haskell says. "I always blow students away with all this stuff."

* 80 inches. Parents, that's the length of the dreaded extra-long twin bed that has become standard issue at many colleges. If that item somehow escapes your attention -- hard to believe, given the frequency with which the colleges offer to sell you extra-long sheets -- your kids are going to find themselves five inches short when they make their bed that first night. The University of Maryland provides the standard 75-inch bed, offering the longer one only to students 6 foot 5 inches and over, but more and more colleges have started giving everyone an extra long. It's just easier. "You never know how many tall people you're going to have, and how many short people, and where they're going to be," says Duke's Hull. "There's too much changing around at the last minute." But some universities see opportunity as well as convenience: Michigan State sells the extra-long sheets as a fund-raiser.

* 80 square feet. That's the size of a two-person bedroom at a New School University dorm on Union Square in Manhattan, crammed with two loft beds, two desks and two wardrobes -- the same size as a standard two-person federal cell, according to the Bureau of Prisons. The two students share a kitchen and sitting area with three others, but prisoners usually get an exercise yard. On less urban college campuses, double rooms average anywhere from 120 to 165 square feet. "If we were building a standard double room now," says Hull, "it would be in the neighborhood of about 220 to 240 square feet for two people." Kids today expect more space, and colleges are competing to please them.

* 208 cubic feet. The capacity of a typical U-Haul, and more and more students are arriving with them instead of the family station wagon or minivan, says Angela White Brown, director of university housing at Michigan State. "The rooms are small [many are 10 by 12] by today's standards," she says. "I'm amazed at how much stuff they get in them. I went by one room one time and there was a full set of drums. I've seen a 63-inch television. Now they like to bring their own furniture -- couches, chairs. Then they bring in their bicycles. They build lofts. An engineering student built a loft that could be raised and lowered." Once Brown watched, dumbstruck, as a full-size commercial moving van pulled up to a dorm. Now, she thought, she had seen everything. She was enormously relieved to discover that several families from Michigan's Upper Peninsula had gotten together on the move, finding it easier to load up and travel the long distance with a group shipment.

* 1,000. Michigan State, which staggers the dates for students to move in, has 1,000 student volunteers on hand to help move 8,000 students into their dorm rooms in one day. "Parking is at a premium," Brown says. "Speed is of the essence. We have a whole army to get everything out of the car as quickly as possible. We can probably unload a car in 20 minutes. Parents love it."

* 2 in 1. Today, many students arrive without ever having shared a room. (Many haven't even shared a bathroom.) Most colleges match them up with minimal information. Early to bed or late? Rock or rap? "It's a random process," says Leonard Brown Jr., director of student life at Loyola College in Maryland, located in Baltimore. "Don't go into this expecting your roommate is going to be your best friend. That can set you up for failure. If you go in expecting this person to respect who you are, the little things become easy to talk about and compromise about."

* 1,650. Duke University has bought 1,650 iPods, giving one to each member of its freshman class this year. Most kids use iPods to download and listen to music; Duke loaded orientation information and the academic calendar into the 20GB devices and wants students and faculty to spend the year experimenting, maybe downloading or recording lectures or language lessons in addition to music. The university's president had a recording of his welcoming address downloaded on them, in case anyone missed the convocation. The project is costing $500,000.

* Two-thirds. A student packing for college should assemble everything and then put two-thirds of it back, says Jan Davidson, associate director of resident life at the University of Maryland. Remember, there's usually no room to store boxes, bags and empty suitcases. Leave the winter clothes at home, and get them over Thanksgiving.

* 1960. Most residence halls were built in the decade that followed that year, as the baby boomers entered college, says Alan Hargrave, director of housing for Ball State University in Muncie, Ind. In recent years, he says, colleges have been frenetically rewiring to accommodate microwaves, refrigerators, computers, printers, PlayStations, DVD players, televisions and cordless telephones, all plugged in at the same time. "Universities across the country are experiencing the first major building boom since then," Hargrave says. "We're looking at more restroom and shower privacy. We're still looking at a mix of double and single rooms. We're looking at grand staircases where students can mix."

* 30. The years spanning a generation. On move-in day, families are pried apart. Parents cry. New students pretend they're not. Sometimes, Loyola's Leonard Brown gets a call from a parent a day or two later fearfully wondering why the child hasn't called. "We have to track them down," Brown says, "and tell them they have to call home." Hargrave says it can take some time to convince parents everything will be okay. "We all did it," he says. "We survived adolescence and young adulthood. But I've always said . . . I could write a book."

* 5/2005. The month the school year ends. The migration begins in reverse. Know this: There will be more stuff than ever.

Author's e-mail: lallyk@washpost.com

Kathy Lally, a former education reporter and foreign correspondent at the Baltimore Sun, will join the college migration next week when she helps her daughter move into her freshman dorm.

Moving day: Overstuffed boxes pile up as first-year students descend on the University of Maryland.