It's a chilly October morning, barely past 9 a.m. in New York City, and already there is a line stretching five blocks from the heart of the Jacob K. Javits Center on 11th Avenue.
Sprinkled in the crowd are superheroes, villains, aliens, robots, dinosaurs and quite a few Marty McFly look-alikes.
For the 10th year, the Javits Center has played host to the New York Comic Con (NYCC), an annual event launched by ReedPOP, an offshoot of event organizer Reed Exhibitions.
More than 167,000 people moved through the front gates and halls of the 840,000-square-foot exhibition space last weekend, quite a bit more than the 33,000 attendees from the convention's first year.
And it's getting bigger.
Tickets for the event went on sale in May and sold out online within five hours. It was the first advance sell-out in the NYCC's history.
Attendance has grown so much, that ReedPOP was forced to expand outside the venue and start a program called NYCC Super Week, involving 89 pop culture events in the city, so that fans who could not get tickets were still able to participate in the convention.
"We're busting out of the building, like literally, they can't contain us—like some sort of Kraken and one of our tentacles is reaching out to the Hammerstein Ballroom, where we have been doing programming all week," Lance Fensterman, senior global vice president for ReedPOP, told CNBC.
And that's not all. New York Comic Con's revenue, consisting predominantly of ticket sales and sponsorships, has increased 20 percent year over year, according to Fensterman.
Comic conventions have exploded into the mainstream in the last few years, bolstering attendance rates not only in New York, but in San Diego and Seattle.
The Emerald City Comic Con in Seattle began in 2003 with 2,500 attendees. This year, more than 80,000 tickets were sold. ECCC's 2016 is already sold out.
San Diego's infamous convention hosts more than 130,000 people each year. The only reason that number hasn't grown is because the convention organizers cannot fit any more attendees into the exhibition center.
Rob Salkowitz, author of "Comic-Con and the Business of Pop Culture," noted in a NYCC panel over the weekend that convention popularity and success is "being driven by the changes in the audience itself. Because fandom conventions are no longer just serving this hardcore geek demographic."
Social media and a new generation of pop culture enthusiasts have altered the stereotypical comic cons of years past, turning the event into an experience rather than just a convention. People have a fundamental fear of missing out, said Heidi MacDonald, editor-in-chief of The Beat, during an NYCC panel.
Eventbrite estimated that fandom conventions grossed more than $600 million in ticket sales in 2013 and have continued to increase.
While the companies that sponsor these events are benefiting from the increase in revenue, so are the hosting cities. Salkowitz, who partnered with Eventbrite, determined that the average economic impact of a comic convention on its host city is eight times the ticket sale revenue, collectively yielding more than $5 billion for local economies.
San Diego Comic Con, however, is an entirely different beast. The convention is estimated to circulate 100 times the ticket sale revenue back into the local economy.
The drawback of this massive and sudden expansion?
"When I first started to go to San Diego Comic Con in 1997, I would get in and I would feel special as part of that fan community. Now when I go, I feel lucky," Salkowitz said.