Against many obstacles — including a pandemic and historic flooding — Day 1 of Made In America kicked off the Labor Day weekend in Philadelphia on Saturday with enthusiastic crowds, a tighter focus on hip-hop and R&B, and new COVID-19-inspired restrictions on attendees that weren’t entirely followed.

Brilliant sunshine swelled the crowd of an estimated 50,000 concert-goers on the start of the two-day music festival founded by Jay-Z and canceled last year because of the coronavirus. The charismatic and tough-talking Grammy-winning Houston rapper Megan Thee Stallion, who performed Saturday night before a stoked audience, was the most anticipated act of the day, and her powerhouse set was followed by surprise appearances by Philadelphia rapper Meek Mill and Lil Uzi Vert.

But while concert-goers couldn’t gain entry without proof of vaccination or a negative coronavirus test, other precautions seemed to fall by the wayside once people were inside the outdoor venue grounds on the Benjamin Franklin Parkway — namely, the mask requirement.

Concert-goers were forewarned this year they would have to give proof of vaccination or a negative coronavirus test.

Once people were admitted, the vast majority did not appear to continue to use masks — nor did there seem to be much enforcement.

A spokesperson for Made In America did not respond to a request for comment about the lack of mask compliance.

Two hours before Saturday’s headliner Lil Baby took the stage, after Atlanta rapper Young Thug warmed up the audience, Stallion appeared just before nightfall, and her fiercely propulsive raps lit a fire under the crowd, delivering a bracing dose of “Hot Girl S—-. "

The rapper kept up the heat, extolling her virtues with the one-two punch of “Realer” and “Freak Nasty,” before intro-ing “Simon Says,” with a soupçon of Philly soul: a sample from Billy Paul’s “Me and Mrs. Jones.” By the time she got to “Wap,” her risqué 2020 single with Cardi B, the crowd was rapping along to every rhyme.

It almost seemed the rest of the night might be anticlimactic. But then, just when R&B singer Kehlani was scheduled to take the Liberty stage, came a surprise with the unannounced appearance by Philadelphia rapper Meek Mill. He followed Stallion on the main stage with his signature “Dreams and Nightmares,” the same song he entered with when he last appeared at Made In America in 2018, just months after being released from prison. Fans who had been leaving the area came sprinting back when they realized Mill was going to perform.

After Meek Mill’s pop-up 20 minute set, Kehlani came on stage only a few minutes behind schedule. In Made in America’s past, that Liberty stage spot was usually occupied by a big name DJ, juicing the crowd with big beats and a light show for the headliner yet to come. Kehlani’s approach was much more subtle than that. The Oakland smooth R&B singer fronted an actual band — a rarity at the fest this year — and she put on a soothing, seductive show that worked as a soothing balm between Megan and Meek, and Lil Baby.

Lil Baby’s extremely loud set drew from the Atlanta rapper’s 2020 album, My Turn, and Voice of the Heroes, this year’s collaboration with Lil Durk, and was highlighted by another Philadelphia rapper surprise (and another Lil).

Midway through his set, Lil Baby brought on Lil Uzi Vert, who has been a frequent MIA presence over the years. Lil Uzi stole the show with his irresistible earworm “XO Tour Llif3”, leading the crowd as it rapped along to its nihilistic mantra, “Push me to the edge, all my friends are dead.”

Mill made one more appearance, joining Lil Baby, whose set ended in spectacular fashion with a fireworks display behind the Art Museum.

The festival started at 2 p.m. sharp on the sunny Parkway with YouTube star and novice performer Destin Conrad on the Tidal stage.

“Thank you so much for this,” the Tampa 21-year-old told a crowd of a few hundred.

City officials and concert organizers forged ahead with the festival despite the worrisome delta variant and rising COVID-19 cases. By contrast, spectators have already been prohibited for the Broad Street Run next month.

If COVID-19 weren’t enough, the region was continuing to struggle to recover from the flooding caused by remnants of Hurricane Ida. Right next to the concert grounds, I-676 from Broad Street to the Schuylkill Expressway — turned into a canal by floodwaters Thursday — remained partially closed most of Saturday as crews continued to remove sediment and debris.

In all, 34 acts will perform on three stages before the festival, which first came to Philadelphia in 2012, ends Sunday night with pop star Justin Bieber.

For people who haven’t been vaccinated and didn’t have a recent negative test, rapid testing was available in tents in front of the Franklin Institute.

Juan Martinez, 21, and Justin Lujan, 19, both from New Mexico, were among those who paid $45 for the test. They were thrilled to pass and get into the show.

They drove three days to get here and spent the last three days around Philly visiting Japanese House and Garden in West Fairmount Park, Camden Aquarium, Geno’s Steaks, and LOVE Park. This is their first trip to the East Coast, and Martinez’s first concert.

While Made In America was the destination for tens of thousands of music lovers this weekend, for Barbara Karn, 78, and Deborah Jackson, 68, of Alexandria, Va., it was something else.

“It was a mistake,” Karn said.

She had read somewhere that jazz saxophonist Ernie Watts was playing in Philadelphia.

“I looked at what festivals were in Philly this weekend and saw this,” she said. “Obviously, he’s not here. I’m not sure where he is.”

Looking over the crowd, she added: “We’re probably the oldest people here.”

Nevertheless, that didn’t stop the friends from enjoying Maeta, an Indianapolis-born rising R&B singer who’s a new signee to Jay-Z’s Roc Nation management company. The 21-year-old R&B vocalist’s 20-minute set showcased an old-school sensibility and her ability to caress a lyric before soaring to dramatic highs.

The Virginia friends said she reminded them of Motown superstar Diana Ross.

After the past week’s heavy rain, winds, and flooding from the remnants of Hurricane Ida, Saturday’s sunshine did not disappoint, and the concert action started heating up in the late afternoon as crowds packed the spaces in front of the main stages. On the Liberty Stage, Buffalo-based rap crew Griselda — named for Colombian drug lord Griselda Blanco — held forth with a bass heavy, dense attack that reached back to 1990′s rappers like the Wu Tang Clan for inspiration.

The gruff Griselda trio of Westside Gunn, Conway the Machine, and Benny the Butcher spit criminally minded rhymes and shouted out South Street cheese steak joint Ishkabibble’s. The crowd — many of them already looking tuckered out from too much festival pre-gaming — stretched out on the lawn and streets before them, with some browsing the strange faux grocery store Wu-Tang pop up set up on the venue grounds to promote the Hulu TV show Wu-Tang: An American Saga.

Two Sixers, Matisse Thybulle and 2021 first-round draft pick Jaden Springer, made an early appearance at the Liberty Stage during the middle of rapper A$AP Ferg’s set. They were in a VIP section. Thybulle posed for a few pictures with fans after A$AP Ferg’s performance. Springer said he didn’t know if more Sixers players would be coming later.

Of course, part of the festival was the side show. And that had its moments, too.

Latifah Lackey, 44, of North Philly, brought her CandyGyrl truck to MIA for the first time.

“I love Jay-Z and how there’s all walks of life here,” she said. “I felt candy would be a good vibe. There’s lemonade and water ice, but I felt like it was missing candy so I’m bringing that.”

Special on her menu was a cotton candy boat with three scoops of cotton candy, Gummi bears, sour Gummi worms, and sprinkles. Enough said. Lackey mentioned that it was Beyonce’s birthday; if Queen Bey was in attendance, Lackey was hoping she would stop by to get a little sugar.

There were other non-musical attractions, too, like what appeared to be the world’s largest game of beer pong (minus the beer) on the festival lawn and a big game of pool kickball (minus the water).

Staff writer Harold Brubaker contributed to this article.