Ah, the serenity of a library on Sunday, that quietest of places on the most quiet of days.

So why did Martin Luther King Jr. Memorial Library in downtown D.C. sound so much like a sports bar yesterday?

“Oh, yeah, go! Go! Go!” shouted a group of men watching the Eagles vs. Giants game in the library’s upstairs hallway.

On any given Sunday, the city’s flagship library is no more serene than your average community center, elementary school or ESPN Zone. This Sunday, parents read picture books aloud in the children’s room, teens lined up to use a mini-recording studio, and anxious Internet seekers checked a waiting list for computer access that was maxed out at 50 names.

It was a busy scene but, for many, a sad one: It marked the end of Sunday hours at the District’s main library. MLK was the last branch in the city, and one of the last libraries in the region, to stay open on a day when so much is closed. Continuing budget cuts mean an end to this Sunday refuge for families, teens and the homeless.

“It’s a real break in tradition. For the first time in more than 30 years, no public library in the District of Columbia will be available to the public for services on Sunday,” said Nancy Davenport, the system’s director of library services. “We know there’s going to be harm. People use our computers day in and day out to look for jobs.”

And watch football. For many District residents, particularly those who live in shelters that close during daylight hours, watching the Redskins at MLK is a Sunday tradition. Many saw it as a cruel irony that the home team wasn’t playing on the library’s last Sunday; the Skins are playing Monday night in Dallas. The fans at MLK made do with the other matchups and plotted ways to catch the action next Sunday.

“We got to find one of those stores with a bunch of TVs in the window,” said Donnie Myer, his guitar case lined up against the wall with the backpacks, duffels and trash bags of the 20 or so other viewers.

“We’ll have to do it old-school,” chimed in Mark Cooper, who lives at the 801 East Shelter in Southeast. “Go to a bar and say we’re all designated drivers.”

Library officials said they have notified service providers for the city’s homeless about the closing of what for years has served as a de facto Sunday shelter.

“It’s been a very important place for them,” said Tyrone McNeal, the supervising librarian Sunday.

Daniel Martu said a Sunday visit to the library with his two daughters has been a fixed part of their weekly schedule for years. He works five days a week at a restaurant in Georgetown, does house projects on Saturday and came to the children’s section each Sunday while his wife worked a shift at Sibley Memorial Hospital. As he flips through a photo book of Canadian landscapes, his girls, Elizabeth, 10, and Bennie, 8, work at adjacent computers.

“We look up books for projects and do schoolwork,” Elizabeth said. At the moment, she was playing Roblox, and Bennie was playing Agent Spin. “We finished our project early,” Elizabeth said, glancing over at her father. “I don’t know where we’ll go next week.”

Sundays are big homework days at the library, said librarian Colleen Semitekol, because so many assignments are due on Mondays. She fields schoolwork questions steadily from opening time to lights out, she said.

“Is there anything in particular about the 1960s you’re looking for?” she asked a young client in a polka-dot hoodie. The girl looks at a paper in her hand.

“No,” she said. “I just need a book about the ’60s.”

The end of Sundays is part of a steady dwindling of public library services in recent years as the city has cut funds. Library spending in the District fell from more than $45 million in 2008 to less than $35 million for 2012. The library system has added 10 branches in recent years, but it has lost 100 staffers and clipped evening and morning hours at all locations.

Sunday hours had already been eliminated at every neighborhood branch, leaving only the downtown shelves accessible at the end of the weekend — and only from 1 to 5 p.m.

The need for Sunday hours is obvious to librarian Margaret Dorsey-Jones. She regularly works at the Parklands-Turner branch on Alabama Avenue, but she saw many of her regular clients whenever she worked a Sunday shift downtown.

“There’s a line out there every Sunday, waiting for the doors to open,” she said.

Many patrons hadn’t heard that next Sunday, the city’s biggest library will, in fact, be silent.

“Closed? All day?” said James Thorton, an unemployed District resident who said he’s been coming every Sunday for more than a decade to read papers and watch movies and otherwise escape a lonely apartment where his TV is no bigger than a toaster. “Man. That’s gonna take some getting used to.”