It’s 7 p.m. on a Tuesday, and there’s not an empty seat left at Stetson’s Famous Bar and Grill on U Street.

The people who have gathered here spend their day as lawyers, government employees and analysts at think tanks. But tonight they go by other names. Bloodthirsty Tyrants. Sausage Kings. Tuesday Heartbreak.

As game time nears, cellphones are shut off, last draft beers are ordered and the buzz in the room rises. Andrew Daniller, a 28-year-old graduate student in a rumpled plaid shirt and a scruff of a beard, rises to greet the crowd. He’s an unimposing figure, but the teams become quiet. The quizmaster has arrived.

It’s weekly trivia night at Stetson’s in mid-April, the fifth week in a 14-week spring/summer league. Trivia nights, also called pub quizzes, are evenings in which people gather in teams to compete to see who has the most knowledge, and at Stetson’s, play in a seasonal league to win a trophy.

For half a decade, trivia nights in the District were independently run, according to the management at Stetson’s. They were held in mom-and-pop bars that didn’t make a fortune from the event but the bar owners enjoyed having the loyal customers who came with the game. The competitions were hosted by quizmasters who were often former players with a passion for trivia.

“It’s a little bit like walking in to Cheers,” said author Marcus Berkmann, who wrote a book on trivia, “Brainmen: The Insider’s Guide to Quizzing.” “You walk in on a Tuesday night, and you know all 20 people in there, because they all come on that night, every week. It’s a great sense of community.”

But now, companies such as Trivia Kings, Brainstormers and Pubstumpers are taking over trivia nights in the District. The companies say they run dozens of game nights each week, hiring hosts and providing rounds of questions to bars looking to fill seats during non-weekend days.

Bill Gelinas, co-founder of Trivia Kings, said trivia is growing at its fastest rate in the District because people are looking for new forms of entertainment. Gelinas estimates that there are at least 60 bars that regularly host trivia in the D.C. area, 24 of which are run by Trivia Kings.

“We’re getting pretty close to the critical mass point where we grow beyond our reach,” Gelinas said.

Berkmann said trivia has gained in popularity because people love to express their knowledge.

“It’s an international sport for the nerd and a way to show off what you know. People come, and they don’t know anything. Then suddenly they know something. It’s a moment of absolute certainty, and they are hooked,” Berkmann said.

But as these trivia companies spread across the city, bars that host independent trivia nights, such as Stetson’s, are trying to hang on to the culture they helped develop. Stetson’s, which hosted one of the first trivia nights in the District, wants to maintain the high-quality questions, dedicated teams and homey atmosphere.

“It’s like hanging out in your living room instead of a big crowd,” said Tommy Osborne, Stetson’s general manager.

Trivia nights began some 40 years ago, shortly after the game Trivial Pursuit was first released, Berkmann said.

“People quickly got bored of playing the Trivial Pursuit board game and just wanted to ask the questions. They starting asking trivia questions at dinner parties,” Berkmann said. “And then the pub quiz just happened, first in Ireland” and then the United Kingdom.

In the District, smaller bars pride themselves on trivia nights so challenging a team might struggle through an entire round.

“The people that play are detail-oriented, and they like to get the facts right,” Osborne said. “Those are the customers we like to have in here.”

Trivia Kings has a different strategy. “Trivia is about entertainment. It’s about getting butts in the seats,” Gelinas said.

The Tuesday Heartbreak team, winner of the last two annual Stetson’s leagues and this year’s front-runner, seems to have cobbled together its dream team almost entirely by accident. Friends joined just because they could.

Brothers Carter Price, 30, of the District and Stuart Price, 29, of Silver Spring are mathematicians. D.C. residents Todd Gregory and Seth Michaels, both 32, work for Media Matters. Cortney Higgins, 32, of the District is the only woman and the player the team views as the glue of the group. And Dave Morrissey, 32, of Arlington County is the one who tackles the sports questions.

“I doubt I would play as regularly with a corporate trivia model. I appreciate the quirky questions that are unlikely to show up outside of the quizmaster model,” Carter Price said.

But Michaels insists a good trivia night depends more on the quality of the quizmaster than whether a company or a mom-and-pop bar is running the show. And that will matter soon at Stetson’s, which is looking for a new quizmaster because Daniller is moving to Philadelphia to pursue a doctorate’s degree in political communications.

“It will be hard to find a quizmaster that matches” Daniller, Carter Price said.

For Tuesday Heartbreak, the love of the game comes from knowing the answers to the tough questions. During a hockey round, Morrissey’s eyes lit up as he realized he could correctly answer all the 10 questions of the round, even one about the 1918 flu pandemic’s effect on the sport.

Throughout the evening, Tuesday Heartbreak soared through the questions. But in the final round, general knowledge, the team faltered on the question: “Where does the alcohol Sambuco come from?”

One player said Spain. Others said Greece. No one guessed Italy.

As the night’s eight rounds came to a close, Daniller announced the final score: Tuesday Heartbreak won, with 88 points of a possible 107. Sausage Kings took second with 84, and Lee Caravello’s Putting Challenge scored 83 to finish third.

“Clearly, tonight’s trivia was too easy!” Daniller bellowed, which made the crowd laugh, acknowledging the trivia was anything but easy.

Michaels said Tuesday Heartbreak loves the challenge.

“There’s a special satisfaction to a really good get,” he said. “And the outcome is always up in the air, so every eureka moment really matters.”