The thump thumping that keeps South Jersey folks up at night isn’t coming from under the bed.

Residents living along a 20-mile stretch of riverfront towns from Burlington to Gloucester Counties have reported noise from what officials call “boom car” parties in Philadelphia. Heavy bass sounds are streaming over the Delaware River and disturbing many who live close to the City of Brotherly Love, causing residents to lose sleep and prompting elected officials in South Jersey to pass measures demanding that Philadelphia do something about the noise.

“It’s a loud booming," Dawn Prince, of Westville, said of the disturbance. "It’s a bass noise more than you can hear lyrics. It sort of rattles the house, like if you crank up the bass on the car.”

From West Deptford and Camden to Palmyra and Cinnaminson, residents report the noise on the weekends, usually from Saturday 11 p.m. until Sunday 5 a.m. This is the second summer most have heard the sounds, believed to be from “boom car” parties, gatherings in which people play music from powerful sound systems inside the trunks of their vehicles.

“It’s like a loud boom system, like they have a concert or something,” said Stephanie Evans, of Pennsauken. “... To hear that and then you can’t go back to sleep, it’s crazy. It’s like nobody can figure out where it’s coming from.”

Michelle Surgner, of Pennsauken, said the music keeps her awake for several hours. But it isn’t only disruptive to her — Surgner’s husband and two daughters also told her they hear the booming sounds.

“It’s so loud and they’re right by the river,” she said of the noisemakers. “It just comes right over here.”

At least two South Jersey towns have adopted resolutions to urge the city of Philadelphia to end the noise.

Gloucester City passed a resolution in July asking Philadelphia to enact harsher penalties for noise pollution and suggesting that law enforcement officials carry decibel meters to better detect noise violations. The resolution called the “boom car” parties a “public safety hazard."

“It’s such a sound that it almost goes through your body, the bass is so intense,” said Gloucester Mayor Daniel Spencer.

He said South Jersey authorities have no real authority to combat the noise in Philadelphia.

“We’re at the mercy of the Philadelphia Police Department to be able to go in and break up these parties,” Spencer said.

Last year, the source of the sound was believed to be in a lot near Jetro Cash and Carry on Pattison Avenue. Ryan Giles, the Westville borough administrator, said that lot has since been locked.

The source seems to keep moving, which Giles said makes it difficult for law enforcement officials to punish those making noise. Westville’s council passed a resolution Monday calling for an end to the disturbances.

“I don’t think Philadelphia even knows where it’s coming from,” he said. “... No one’s ever really pinpointed exactly where the location is.”

Deana Gamble, the communications director for the Philadelphia mayor’s office, said that the office is aware of the noise pollution complaints and that police are “taking necessary steps to address it.”

As of Friday, she said, the city has received Gloucester’s resolution but had not yet received Westville’s measure.

Philadelphia police enforce the city’s noise ordinance, which includes quiet hours between 9 p.m. and 8 a.m. Those who violate city code face fines for a first-time offense between $100 and $300. Four or more offenses could cost $500 to $700.

“We certainly understand how frustrating it must be for our neighbors across the river,” Gamble said. “The city is looking into the cause and specific location, and engaging local partners to see how it can be addressed.”

Palmyra Police Chief Scott Pearlman said, “I’m not sure how much Philadelphia can do. We’re going to take any assistance they can provide us.”

Philadelphia police declined to comment.

Capt. Brian Hartzell recently told the Courier-Post that authorities believe groups are coming from around the tri-state area, as far as New York, to drag race and watch with “boom cars” late at night.

Hartzell told the newspaper he assigned multiple officers to patrol the stadium area one July weekend. The officers reported that about 100 cars showed up around midnight and authorities “issued a bunch of citations.”

The Westville police department wrote Friday on Facebook that Philadelphia police “advised that they are aggressively addressing the ‘boom car’ situation that is affecting the residents of New Jersey with the loud thumping noise. The lots in which the boom cars have been gathering have been locked down."

It seems the people creating the noise “are just getting joy” out of aggravating those living across the Delaware River, Prince said, but South Jersey residents have organized to take the matter into their own hands.

Several people said they have contacted their respective towns and Philadelphia officials to address the noise. One Facebook group dedicated to airing grievances about the disturbance has more than 330 members and numerous posts detailing complaints about the nighttime booming.

“The people of New Jersey are just going to keep fighting this," Prince said.