The festival came as the strike moved into a fourth day Friday. Trash has been piling up in some areas, and more than 30 Medical Examiner’s Office staffers have been ordered back to work because of a growing backlog of bodies in storage.

Sullivan, a Philadelphia native and Grammy award-winning artist, said in a post on Instagram on Friday that she would stand with the striking workers “until the city and the union find a way to bring fair living wages to our working class. I love my city and I believe in you,” she wrote. “Hopefully we will get to celebrate when things are better.”

The latest talks between the city and leaders of District Council 33 — the largest of four major unions representing city workers — ended late Wednesday. Both sides have said they were willing to continue negotiations. The union represents many of the city’s blue-collar workers, from trash collectors to clerks to security guards. Police and firefighters are not on strike.

The city has offered a three-year contract with annual raises of about 3%, which the union said amounts to little more than $1,000 after taxes for members making $46,000 a year on average.

Mayor Cherelle Parker has said the city has “put its best offer on the table.” She stressed that the effective 13% pay hike over her four-year term — including last year’s 5% bump — along with a fifth step on the pay scale would be the best contract the union has seen in decades.

Parker responded to LL Cool J’s statement, saying that she spoke with him on Thursday.

“I respect his decision, and understand his desire to see the city unified,” the mayor said. “He is always welcome in Philadelphia.”

The union also responded, saying LL Cool J’s support for municipal workers “highlights his commitment to social justice and community well-being.”

“His support not only brings attention to our efforts but also inspires others to recognize and advocate for the rights and respect of all workers,” the union said. “It’s heartening to see public figures using their influence to champion causes that matter to everyday people.”

On Thursday, Common Pleas Court Judge Sierra Thomas-Street approved the city’s request to have the medical examiner’s office staffers return to work because bodies have been piling up there in storage, posing a health and safety risk. Those workers include death and forensic investigators, forensic technicians and clerks.

The order came a day after the judge ordered some emergency service dispatchers and essential water department employees back to work.

Mounting trash piles in some parts of the city were also still causing grief for residents and officials, who have strongly urged residents to follow the collection guidelines imposed when the strike began Tuesday. They also urged residents to report problems at the trash collection sites, and noted trash is being cleared as fast as possible and the city is working to open more sites.