The coach bus lurches against the curb of Dupont Circle during rush hour Friday and, instantly, invisible lines are drawn. Insiders here. Outsiders there. A swarm of publicists and rent-a-cops defends this battlement with raised voices and outstretched palms against Washington, which is walking home from work. Washington has seen the scrum at the front entrance of the Washington Club, and Washington has stopped to check it out.

“Everybody, I need you to move off the sidewalk,” demands a blazered event manager whose head is wired with a Secret Service-like earpiece.

“Folks, you need to get on the sidewalk,” orders an officer from the Metropolitan Police Department, who just arrived to determine why exactly a giant coach bus is clogging Dupont Circle.

Answer: To disgorge a bolus of B-list celebrity.

Observation: Washington is very good about not giving a damn while secretly giving a damn. The weekend of the White House Correspondents’ Association Dinner raises the fault lines of insideriness to the surface. It’s easy to ignore invite-only Washington every weekend of the year except this one, when limo lines and red carpets unfurl in the most pedestrian of places.

“What’s the event?” asks a guy walking his husky in front of the Washington Club.

“We don’t know. We’ve been trying to figure that out,” says a woman on her cellphone. (It’s a cocktail hour for the showbiz activist outfit Creative Coalition.)

“You’re star-struck,” says another passerby who has yet to pass by.

“I know. I’m a loser,” says his girlfriend, craning her neck at the red carpet, which, in capital fashion, is Cabernet-colored instead of red, and short.

Down the steps of the coach bus slinks TV star Alyssa Milano, who was in that show, whatever it was.

“Ms. Milano, Ms. Milano, will you sign this please?” says an older gentleman wearing baggy khakis and a beige baseball cap. He took the Metro in from Silver Spring with his wife, Judy, to stake out the event. Both retirees have a clipboard of celebrity portraits — alphabetized, with Patricia Arquette on top — so they can wrangle autographs for his extensive collection (10,000 signatures collected over 50 years).

“Larry King used to do his TV show from Washington and we’d call and they’d tell us who was going to be on and then we’d wait outside the door,” says Judy, who, like her husband, wishes to remain anonymous because they like being at the edge of the spotlight, not in it. “It used to be a lot better here. Now there are dealers, and celebrities have gotten used to seeing their autographs on eBay.”

Avast, the pathetic periphery! (Not being judgy; we’re here, too.) The inquisitive, slightly embarrassed borderline to import! Where the curious linger with their noses in the air, where glommers-on glom on — but only long enough to get a whisk of a Sharpie or a blurry digital snapshot with yesterday’s hot new talent.

The bus, clown-car-like, coughs up a semi-celebrity about every 90 seconds. Omar Epps. Cheryl Hines. America Ferrera. In binders in the den at home, Judy and her husband have the signatures of Lillian Gish, Clark Gable and Claudette Colbert (whom they once chatted up in the lobby of the Watergate). Now they stalk Michelle Trachtenberg and the “half” from “Two and a Half Men.” Neither deign to sign their signatures as they move quickly toward the runty red carpet, which serves as a petting zoo for journalists.

Most of the people coming out of the bus are worth between $12 and $20, autograph-wise, according to a curly-haired Baltimorean who won’t give his name because he’s the kind of spoilsport dealer Judy’s talking about. He stalks around, panther-like, testing the integrity of the perimeter. He drove down because of the sheer quantity of celebrity this weekend provides.

“This is very low-end, but I’m here because of the numbers, the volume of people,” he says, adding that he can make up to $65,000 a year by selling autographs online. “When Obama took over, D.C. became more of a magnet for star power. The one problem is TMZ. Now that they’re here with their cameras, I just become background noise.”

With the last of the stars in the Washington Club around 7:15 p.m., Judy’s husband takes a seat on a fold-out chair. How long is he going to stick around?

“Till they come out,” he says. Judy, looking weary, watches the traffic spin around Dupont.

The fault lines between fabulous and pedestrian crack and splay outward from there. There’s Jesse Tyler Ferguson of “Modern Family” coming out of the Jefferson Hotel, hand-in-hand with his actor boyfriend, Justin Mikita, and walking past a trio of 20-somethings on 16th Street NW at 7:45 p.m.

One of them, seeming astonished, blurts out: “It’s that guy from — ”

“STOP,” shushes his friend, embarrassed.

Pop beats thump upward from the Astor Terrace of the St. Regis Hotel down 16th at 8:30 p.m. The sound of the People/Time magazine party is audible from the sidewalk, where the uninvited wait for the S2 bus to Silver Spring. A gaggle of young women loiters near the valet attendants. Are they here to people-watch? No, they say. Please.

And yet here they are, several hours later around 11:15 p.m., pacing and craning outside Long View Gallery on 9th Street NW, where the Atlantic and the National Journal and Funny or Die are hosting a “First Amendment Party.”

Okay, the gawkers admit: They are exercising their First Amendment right to assemble peaceably in the name of hounding Chace Crawford. They’re here to get as close as possible, to extend a hand across the celebrity-nonentity chasm, which narrows considerably in this town on this weekend. There are four of them, and they drove in from the University of Maryland — as they’ve done each of the past four years — because this beats pizza in the dorms.

“This is the only time these people come to town,” says Hannah Allison, 20, an engineering major. “And we’d be hanging together anyway, but this way we can do it with celebrities.”

“This weekend is on our calendar, circled, for the entire year,” says Naomi Tesfai, 19.

Then Bradley Cooper walks right into them. They explode. They chirp his name and trigger their flash-bulbs and put their arms around his shoulders and send instant updates to their Facebook pages. A rent-a-cop asks them to please step back from the velvet rope. They have breached the perimeter.

“Amy, get ready, a limo’s backing up,” Allison says as they regroup.

How long are they going to stay here?

“Until we see Chace,” says Amy Vitale, 19. They plan to be camped out at the Hilton at noon the next day for the actual dinner, which starts at 7:30. They’ll be bringing homework.

The autograph dealer from Baltimore is nearby, as are a couple of paparazzi, who leap into attack mode when Rashida Jones and Rosario Dawson teeter out arm-in-arm, cross the street and head south, busting the perimeter momentarily as gawkers trail them and traffic jams up. Jon Hamm follows soon after, and then Sean Penn. They all reassemble at the Passenger on 7th Street, near the convention center, after midnight. Penn ducks into a back alcove for drinks. Hamm bellies up to the main bar, unmolested.

As a friend reported from the scene: “I think he picked a good bar, full of hipsters who are too cool to act star-struck.”

The ladies from the University of Maryland are indeed in position at 5 p.m. Saturday, pressed against the gate in the valet drop-off area of the Hilton, flanked by a regiment of other onlookers. The raised terrace of the Courtyard Marriott across Connecticut Avenue also serves as bleachers for gawkers. Inside, slipping through the honeycomb of pre-dinner receptions, is the autograph dealer from Baltimore. He’s in a tux. He’s crashing the cocktail hour, snapping photos of celebrity guests. How’d he get in?

“I have my ways,” he says.

After the dinner, outside the French ambassador’s residence around midnight, two dozen non-VIPs jockey for proximity to queued-up VIPs. Among the former are Judy from Silver Spring and her husband, clutching their celebrity portraits, peering through the iron gates at the gorgeous, illuminated mansion. Close enough.