In the '50s, Bill Haley used to "rock this joint."

Nashville has country and western. Liverpool gave the world the Beatles. And now a South Jersey town - Gloucester City - says it's the birthplace of rock and roll.

Says who?

Bill Haley, that's who. And now Gloucester City is bringing it all back home.

(OK, that was Bob Dylan, but just stick with me.)

On July 14, Gloucester City is throwing a free rockabilly concert at the corner of Broadway and Market Street, 2 to 7 p.m., outside Jack's Bar & Grill, to celebrate this working-class burg's little-known but arguably significant role in the development of rock. A mural outside the bar is planned, and, during the concert, a plaque will be unveiled proclaiming Gloucester City's newly noted claim to fame.

It turns out that for about 18 months in 1951 and 1952, Haley and his country band, the Saddlemen, played at Jack's when it was the Twin Bar, mixing country and western with rhythm and blues, according to the research of a motley crew of local characters.

A biography coauthored by the rock legend's son John noted that during the Twin Bar gigs, Haley's "version of 'We're Gonna Rock This Joint Tonight' would vibrate off the walls so hard you could feel the music!"

"Rock This Joint," released in 1952, begat "Rock Around the Clock," and the Saddlemen became the Comets. In a recording played at a news conference yesterday to announce the concert, Haley, who died in 1981 - and who is described by some as "the father of rock and roll" - explained how his sound came to evolve at those early sessions at the Twin Bar.

A few disclaimers:

Some would argue that while white musicians got the fame, black artists were rock's real pioneers.

And on the birthplace thing, Gloucester City is not the first to lay claim. Try Wildwood, Memphis, Cleveland, and Hattiesburg, Miss., to name a few.

But Gloucester City is happy enough to be in that company.

"I think we have a legitimate place at the table," said Paul J. Kain, city administrator for the 11,000-resident riverfront town. He was among those who researched the city's rock roots, and he sees good things ahead.

"We're hoping it'll help to promote the town," said Kain, a former Mummer. "It's always been considered a blue-collar, hardworking, sometimes hard-playing town. But it's the town, at least in this area, that gave the impetus for this kind of music."

Haley, by the way, lived in Chester, event planners said. The Rock and Roll Hall of Fame's Web site notes that Haley and the Saddlemen had a regular radio show there.

Kain said he tried to persuade the bar's past owner to do something with the Haley history, but no dice.

In late 2004, Dennis and Tammy Galligan bought the Twin and renamed it Jack's, after Tammy's late father, a former drinker who gave up the sauce all but one night a year and then only at one place: the Twin Bar on New Year's Eve.

One day, Wayne Young, an aircraft mechanic and music lover from Northeast Philadelphia, came in and tried to talk up the Haley connection.

"I blew Wayne off, and I sent him on his way," Tammy admitted.

But not long after, Marshall Lytle, one of Haley's old band members who plays with the still-rocking Bill Haley's Original Comets, stopped by. The Galligans started to believe.

The Galligans are now redoing the tavern's facade, with the help of some city funds, to resemble its former self. They're renaming it Jack's Twin Bar.

"We don't have any high hopes of being a Stone Pony, but we don't know," said Dennis Galligan, referring to the famed Asbury Park venue. "We'll see what it brings us."

Yesterday brought city officials, supporters and a smattering of media. Charlie Gracie, a South Philadelphia native and Drexel Hill resident whose "Butterfly" was a hit in 1957, played some of the oldies.

"It's nice to be here. At my age, it's nice to be any place," quipped Gracie, 71. He said still does gigs, including abroad. He will be performing July 14, along with the Original Comets, Tommy Conwell, and Full Blown Cherry.

Also on hand was Danny Vanore, also of South Philly. He said he was named for his late grandfather, Danny Cedrone, a friend of Haley's who played that famous guitar solo on "Rock Around the Clock."

"I just came back from Cleveland," he said. "My grandfather's guitar is on exhibit there."

Carlos M. Alvarez, also known as radio personality King Arthur, said he plans to broadcast the July 14 concert. Married to one of Cedrone's daughters, he said he'd always heard about the Twin.

"Man, did my hair stand up when I walked in the door," he said. "It was as though the spirits came up. 'Yo, man, where've you been?' "

To view a slide show from Jack's Bar & Grill, go to http://go.philly.com/rockandrollEndText