By 2 p.m., the line stretched halfway down 45th Street. They sat wearily on the pavement, tiny backpacks slumping on their bare shoulders, large, pleading cardboard signs by their sides. Some had been there since 10 in the morning; most had been waiting, in a sense, for weeks, and by now the heat and the noise of the city barely registered.

“This ain’t nothing,” you hear one girl, a real veteran, say. “I’ve seen so much worse than this. I was here when Backstreet came by and, man, that was dangerous. You don’t want to be here when that shit goes down.” Her audience, three wide-eyed young women from Florida, nods in understanding.

They’ve come from all over — Texas, London, Staten Island — to be in Manhattan today, their tired, huddled masses sprawling onto Broadway like a teeny-bopper crossroads of the world. Mostly female, their ages range from 16 to 22 — as required — with a couple of hopeful scofflaws thrown in. Nearly all are there with friends. The MTV studios — in the Viacom building at 1515 Broadway — loom above the crowd like a musical Mecca as the teen hordes scream, willing Carson, the great caliph of teendom, to answer their prayers of fleeting stardom.

Welcome to the world of “Total Request Live.”

“Total Request Live” — or “TRL,” for those in the know — is a video countdown series begun in 1998 in response to critics who wanted the “music television” back in their MTV. Hosted by deadpan dreamboat Carson Daly, the hour-and-a-half show plays 10 videos a day (plus occasional “wannabes,” videos selected by the MTV staff for potential appearances in the top 10, and “close calls,” videos that don’t quite make the cut) chosen by fans who write in to the official Web site or call a hotline. Videos are rarely shown in their entirety, and are often interrupted by e-mails rolling across the screen or filmed shout-outs from audience members.

“TRL” prides itself on its interactivity, but both the show and its fans — although not its critics — realize that the videos are beside the point. “TRL” is an experience, a generational touchstone, regardless of the virtues of the series itself. The show’s many teenage deplorers were lined up that day with equal resolve. Of the hundreds of teen and college-age kids gathered on 45th Street, few were there to watch videos, or even to see the stars in residence that day: Willa Ford, the oddly controversial teen singer, and, more poignantly, Aaliyah. Rarely did a teen girl utter, “I want to see Carson.” The most popular request is “I want to see me.”

This is a generation younger than MTV itself, raised in the shadow of reality TV and instant celebrity. On the afternoon of July 17, they were prodded, cattle-like, through a studio, made to shout inane pieces of dialogue on national TV and told to request videos for bands they didn’t even like. But what makes this group different from, say, their flannel-wearing predecessors is the savviness with which they do so. While older music fans profess outrage for MTV’s blatant commercialism, the “TRL” audience blows off such concerns as irrelevant. The goal, obviously, is to get on TV. “TRL” may claim to mark a return to videos, but in the end it’s just another reality series.

Here is the story of a day behind the scenes.

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“I’ve seen so many celebrities since I’ve been here,” says Justin, a Texas teen in New York for the week to visit colleges. “I saw J.Lo, and that chick from ‘The Sopranos.’ The best was seeing Matt from ‘Real World New Orleans,’ though. I got his autograph and had my picture taken with him; it was awesome. It was like we knew each other.”

Justin is a big fan of “The Real World,” and of all reality series, for that matter. He recalls with regret the day he painstakingly filled out an entire application for the newest edition of “Survivor,” only to discover he didn’t meet the age requirement. “The minute I turn 21, I’m going on that show,” he says with a sigh. Today, the goal is more feasible: to get on “TRL,” preferably, in the front lines, where cameramen can track his every “Wooo!” Justin had tried to attend a taping yesterday, but had to settle for a J.Lo T-shirt (“Now, everyone can be sexy,” it says on the back) and his name on the MTV reservations list instead.

Behind Justin, two other Texas girls are gazing at the scrapbook of a local city teenager, which is filled with pictures of herself with various “TRL” celebrities. “I have been on this show so many times,” she says. “Here’s me with LFO — aren’t they hot?” Boy band members grin beneath the photo album plastic. “And I’ve seen Britney, and Shaquille O’Neal, and Lil’ Bow Wow …”

“So do you have reservations?” asks Nadine, one of the girls from Texas, putting a large, hand-painted sign on the ground: “TX loves TRL.”

“Standby,” the girl responds, referring to the line for those without advance seats. “I’m hoping they’ll bring me up, but I’ve been here so many times.” The Texas girls nod appreciatively. “So,” she asks, “who’d you sign up with? Courtney?”

Courtney Mullin is a member of the MTV staff both loved and feared by the “TRL” crowd. Blond and beautiful, Courtney is so legendary that many of the male “TRL” fans — who made up roughly 25 percent of those in line — were there to see her. (“I’m here to see my girlfriend Courtney,” a 14-year-old told me while his friends convulsed in laugher. “She’s going to pretend like it’s a Popsicle. Boo-yeah!”) Inside the studio, Mullin runs the cool events, like the dance contest. The female fans often view her with terror.

“No,” says Nadine. “My girl looked like Kelly from ‘Survivor.’”

“That’s funny,” chimes in Justin. “Because my girl looked like Colleen from ‘Survivor’!” They laugh.

On 45th Street, a Pakistani cab driver leans his head out the window. Like all New Yorkers, he knows “TRL,” but unlike most New Yorkers over the age of 25, views it with something other than pity and disdain. “Who is on today?” he asks.

“Aaliyah,” the crowd shouts back.

“Oooh, Aaliyah. Where is she?” The Pakistani is excited. He is a big fan of “Romeo Must Die.”

An NYPD officer glances at the cabbie warily, then wipes his brow and stares into the sky. The Times Square station is a few blocks away from the MTV series, and at this point, it’s almost necessary. A 1999 appearance by the Backstreet Boys nearly shut down Midtown. Many officers resent taking on the “TRL” beat, even in this Giuliani era. “I feel like a fucking babysitter,” said one, who requested not to be named.

In many ways “TRL” is emblematic of New York’s changing face — 10 years ago the sight of a group of scantily clad teens screaming into the air would probably be attributed to less innocuous circumstances. The audience in line that day, however, knows no other New York. For many, their first real look at the city came from the second-story view of Carson Daly’s window.

By 2 p.m., the massive crowd had separated itself into two lines, one guest list, one standby. Desperate standby fans, mainly out-of-towners leaving the next day, regularly offer money for a coveted position. On the rare instances this ruse works, it leaves everyone out in the cold. MTV is stringent about its guest list. Angelica, a 15-year-old Hispanic girl from Brooklyn, asks to borrow my driver’s license. “I’m going to cover the picture,” she explains. It doesn’t work. A boy from Honolulu offers $100 for my place in line. He has been waiting since noon, and although standbys are eventually taken, he will not be one of them.

Back in the guest-list line, Nadine and her friend Vicki are trying to figure out who the other musical guest is. “Wilma? Willa something?” she wonders. “Willa Feared?”

“Willa Ford,” says a girl in front of her, an angelic blond wearing a pink tank top. “But she’s a motherfucking bitch. You know she beat up Nick? From the Backstreet Boys? Fucking skank.” (Hating Ford is a popular activity among some teenagers.) She rolls her eyes, which are covered in purple glitter, angrily. “And I don’t even know who Aaliyah is.”

The blond, however, is alone in her assessment. Willa Ford should be the stuff of “TRL” legend: a vampish Britney-wannabe, she’s more known for her boy-band boyfriends than her debut single, a song titled “I Wanna Be Bad.” MTV had played up her appearance with an interview with a dazed Nick Carter, and a segment in which Ford gave a thinly veiled dis to Britney Spears and Christina Aguilera. It’s a made-for-MTV controversy about a made-for-MTV star, a seeming bull’s-eye. Plus, the video is set in a strip club. How could it miss?

But few knew, or cared, about Willa Ford. Even hardcore Aaliyah-ites were difficult to find. Nadine confessed she knew little about either artist, and had, in fact, only seen the show four or five times. Vicki nodded in affirmation. So why are you here? “Oh, come on,” she laughed, her braided hair bouncing, “It’s ‘TRL’! You have to go at some point!”

What about Carson? “I guess it would be cool to see Carson,” she admitted. “But really, I don’t care. I just want to be here.” The bands, the host, in a sense the series itself: all beyond the point.

Nadine is distracted by the appearance of the MTV staff, who are carrying French Connection bags filled with clipboards and blue plastic bracelets. A collective “Oh, my God!” goes through the crowd as MTV employees step up to the younger crowd like counselors at the coolest summer camp ever. After taking my name and checking my ID, they hand me a sheet of paper. “Fill this out,” a 20-something girl — the Kelly from “Survivor” look-alike — tells me as she fastens a “TRL” access bracelet around my wrist. I open it.

“What kind of Aaliyah fan are you?” it asks. “Circle one.” There are three options: “Fanatical Fan,” “Huge Fan” and “Fan.” Next to the query is a picture of Aaliyah, looking seductive. To the right: “Why do you like Aaliyah?” There are four lines for the response. (This was several weeks before the young singer died in a Bahamas plane crash.)

Everyone is circling “Fanatical Fan.” This, it is explained, is so they might get on the show “Fanatic,” an MTV documentary series exploring teen celebrity devotion. But what if you don’t like Aaliyah, or really know who she is? Circle it anyway, they advise. Who knows, they might even use it on the show today. Maybe you’d get to meet Aaliyah! Do you know how much airtime that would be? But what if they pick you, and you don’t have anything to say? It doesn’t matter, they assure me. They’ll help you.

“Help” from MTV, I later found out, is tantamount to regimented instruction. But that was to come later. Now a new MTV staffer, armed with a Polaroid, was making the rounds. He asked me where I lived. “Queens,” I replied honestly, and he proceeded to take my picture. “Write down your name, phone number and your favorite ‘TRL’ artist. We’re keeping you on file,” he says ominously, and walks away.

“Oh, my God!” says Nadine. “That’s so cool. They’re going to keep it because you’re local, so when your favorite ‘TRL’ artist comes back, you might get to return to the show.” She looks down at my picture. “Britney Spears,” she says with an approving laugh. “Man, I wish I lived in Queens.”

The inside of the MTV studios looks like a shopping mall, with glassy windows and an escalator leading into a more businesslike hallway. Following the opening of the doors at 3, we are herded into a dark corridor. MTV staffers glare at us from every side, blaring instructions as we go.

The guests on “TRL” are referred to as “the talent” — as in “No one is to touch the talent. No one is to speak to the talent. No one will ask the talent for an autograph, and therefore, no one will be kicked out of the studio.”

Behind me, a group of teen boys smirk. “But what if ‘N Sync’s there?” High five. The boys will be asked to leave before even entering the studio. While boy-band dissent is widespread among the “TRL” crowd, here you’ve got to go with the flow. Inside, we’re all ‘N Sync fans. MTV blames their removal on not enough space.

Any unease over the sudden expulsion, however, is quickly forgotten. It’s time for the most important part of the “TRL” experience: shout-out rehearsal. Of all the many, many “TRL” qualities destined to annoy discerning audiences, the shout-out is the grand poobah. It is a phenomenon often attributed to the sad, sorry attention span of Generation Y: products of the MTV/Internet/Michael Bay era, they simply cannot sit still for the duration of a video without bursting into an exuberant squeal over said video’s contents.

In a sense, this is plausible. “TRL”-style shout-outs in the sanctimonious grunge era — “Hi, I’d like to request Alice in Chains’ ‘Man in the Box’ because it made me question the value of the human soul! Woooo!” — probably wouldn’t fly.

But to attribute “TRL’s” most interactive qualities to its audience would be to misunderstand both the series and its fans entirely. “TRL” shout-outs are scripted to the letter by Gen-X grown-ups: Participants are told which video they like and exactly why they like it. In exchange, camera-loving teens are awarded precious airtime. It’s a winking, knowing trade, perpetuated in part by the staff’s attempts at letting teens choose their own opinions before being inevitably overruled.

“When you say your shout-out, try to be unique,” stresses an MTV employee. “Do not use the title of the video in your shout-out. You do not love Backstreet because they’re more than that, you have no desire to batter up like Nelly and you do not want to see Destiny’s Child because you are bootylicious.”

The crowd nods. They are not bootylicious. Got it.

An MTV staffer observes the crowd, his gaze finally resting on an eager-eyed blond named Michelle. “You like Backstreet Boys,” he pronounces. “Now, why do you like Backstreet?”

“Hi, my name’s Michelle, I’m from South Carolina and I like Backstreet because I love their music and their new video rocks!” the teenager says on cue.

“Mmmm. No,” says the staffer, sighing heavily. “First of all, you forgot your ‘Woooo!’ You have to ‘Woooo!’ at the end of your shout-out. Don’t ever forget to ‘Woooo!’ Now, which Backstreet is your favorite?”

“Um … Nick!”

“How about Kevin? Can Kevin be your favorite?” Nick is so passé.

“Sure, OK!”

“Let’s see: How about, ‘Hi, my name’s Michelle, I’m from South Carolina and I want to see Backstreet’s “More Than That” because I love Kevin and he rocks my world!’” says the staffer, a burly black man with glasses. “Let’s try that again.”

Michelle gives her shout-out word for word, but forgets to scream enthusiastically at the end. Two MTV staffers look at each other and shake their heads. Michelle’s shout-out will not make it on the show.

Nadine from Texas has raised her hand and is grinning wildly.

“You,” says the staffer. “You like Blink 182.”

“Total Request Live” is essentially limited to three types of music: teen pop (‘N Sync, Jennifer Lopez, Britney Spears), rap (usually dance-flavored, like Nelly or Lil Romeo) or pseudo-punk “number bands” like Blink 182, Sum 41 or Eve 6. The show’s lack of variety at times recalls MTV’s early days, where Rod Stewart’s visage appeared in a continuous loop. Since the show’s debut nearly three years ago, only 20 different artists have made it to No. 1. Many have had to be “retired” out of the countdown after remaining there for 60 days.

The lack of variety, for the audience, is as meaningless as the concept of music itself. Packaged bands like Dream and the Backstreet Boys hold stage with reality TV bands like O-Town and Eden’s Crush — groups consisting of members who were “real people” mere months before. Teen pop is, in a sense, as democratic a form of music as you can get. The playing field has been leveled and the process of joining a band has been stripped of all mystery and illusions of integrity. It’s not about the music, it’s about them, it’s about fame, and for “TRL” fans, that’s just fine.

“Hi,” Nadine is saying for the fifth time. “This is Nadine from Texas, and the reason I love Blink 182 is because they are so spontaneous, and you never know what they’re going to do next. Woooo!”

The studio in which “TRL” is filmed is smaller than it seems, and so is Carson Daly. “TRL’s” home base consists of several bleacherlike seats and a small enclave, where Daly counts ‘em down and is visited by “special guests” who “worked really hard” to get there. (Among that day’s elite was the president of the “TRL” Fan Club.) MTV places me in the front row center next to two impeccably made up girls from Alabama. Britney blares from the speakers as teens dance, chat and pester the MTV staff for better seats. “Please, I’ll do anything to get on TV!” they cry. Bored cameramen elbow each other and wink.

Courtney appears, blond and beaming. She asks how psyched we are to be there today. We are not psyched enough, and as the audience gains momentum, Courtney reminds us that those exhibiting unacceptably low levels of enthusiasm will be moved off camera. We scream like she said the secret word.

An MTV employee quietly approaches Cali, one of the girls from Alabama. She explains that today they’re doing a “Wheel of Fortune”-style game with members of the crowd outside holding individual letters. Throughout the show, fans and guest stars will guess letters until the puzzle is solved. Cali happily agrees to join Carson in the “TRL” game.

“Can I guess an S?” she asks. The MTV staffer checks her clipboard. There is an S, she notes. After conferring with a fellow employee, she nods her approval. Like every other aspect of the show, this guessing game is scripted from beginning to end, down to the letters contestants may pick. MTV makes no attempts to cover its tracks. There is no reason to. The audience, confident in the merits of this trade-off, will always acquiesce.

It’s a mystery what the MTV staff, 20-somethings raised in a musical era in which “integrity” and “individuality” became keys to marketability, think of their role as guardians of the teen pop set. Poker-faced in person, they’re often seen smirking, eye-rolling and giggling behind the scenes. The rise of “TRL” and teen pop happened simultaneously, one feeding off the other until all traces of grunge were scrubbed away. In a sense, “TRL” is the ultimate revenge. When Britney sings “What You See Is What You Get” or J.Lo claims “I’m Real,” does it have more veracity than, say, a Versace-clad Courtney Love? The concept of “selling out” is wholly obsolete, and therefore the integrity of the audience is not expected or encouraged. The only point of self-assertion is accumulation of airtime, and everyone at “TRL” knows it.

No one epitomizes this more than host Carson Daly. Satirized on “Saturday Night Live” by Jimmy Fallon’s opening of “Hi, I’m Carson Daly, and I’m completely average in every way,” the reigning prince of MTV is savvier than you’d suspect. “Man, there’s nothing I like better than a new video from O-Town,” says the 28-year old Daly, grinning brightly. Carson asks the tough questions, like what it means for Willa Ford, really, to be bad. His eyes light up when Cali talks of the “little Arab man” who took her on her first New York cab ride. And yet there’s a genuine appeal to him, the sly sweetness of a guy who simply decided to lay back and let the teen tide take him away.

And so the show goes on. Fans deploring Willa Ford overwhelm her with cheers upon her arrival. The puzzle is solved: “The Stars of Pop Are Back on Top” and ‘N Sync are No. 1 yet again. Bailey from Texas appears in the middle of a Sum 41 video to tell us she’s “pumped to see Sum 41 because they know how to turn ‘TRL’ into a mosh pit.”

The atmosphere, in its very falsity, is contagious: Why not wave your new Mariah Carey single in frenetic excitement on national TV? The justification is the very fact that you are there.

You don’t go to “TRL” to hear music, you go to “TRL” to be part of “TRL” — or to see yourself in its image, a screaming fan all too in the know. If video killed the radio star, then “Total Request Live” has killed the video, replacing it with its fans’ desperate grasps at fleeting celebrity. This is MTV’s real “Real World,” and people have started being polite.

For Carol Burrell, running a Web site was just another step in a long life of sci-fi, fantasy and horror devotion. Her fannish enthusiasms began in early childhood, when family dinner was scheduled around “Star Trek” reruns and horror stories were read before bedtime.

The magic of these fantasy worlds proved alluring, but even more appealing for Burrell was the communal, participatory nature of fandom itself. “I wanted to be part of that world, the world that creates that kind of entertainment,” says Burrell.