WHEN IT comes to the history of Atlantic City, Nelson Johnson literally sees things in black and white.

Johnson, an Atlantic County Superior Court judge from Hammonton, N.J., is the author of Boardwalk Empire, which plotted Atlantic City's storied tale by focusing on the white power structure from the town's founding in 1854 through the current casino era. The chapter about early-20th-century political and underworld boss Enoch "Nucky" Johnson was the inspiration for the HBO series of the same name.

Tomorrow, Medford, N.J.-based Plexus Publishing releases Johnson's The Northside, a parallel history of AyCee's African-American community.

Not just a chronological look at Atlantic City's black history, the thoroughly researched, somewhat scholarly (but still eminently readable) Northside presents a compelling argument that the seaside resort could never have achieved its iconic status had it not been for the black citizens who, in the town's early-20th-century heyday, accounted for some 95 percent of the tourism industry's workforce.

It likewise explains - via the stories of notable black citizens like baseball immortal John Henry "Pop" Lloyd and groundbreaking women's personal-care entrepreneur Sarah Spencer Washington - how this situation made the area (roughly bounded by Atlantic Avenue on the south, Absecon Boulevard on the north, Connecticut Avenue on the east and Arkansas Avenue on the west) unique in African-American history.

Johnson had already written about the Northside in "Plantation by the Sea," a chapter in Boardwalk Empire. But by his own admission, that did not adequately tell the story.

"The Northside really is an offshoot of Boardwalk Empire," explained Johnson. "When I was researching Boardwalk Empire, I came to the slow realization the history of the black community was really [important]. I recognized that nobody else had even tried to tell this story."

Not that Johnson necessarily wanted to be the one to do the telling. Being white, he was hesitant. But lobbying by a person who was to become a crucial source ultimately changed his mind.

"All I can say is, I met a gentleman named Sid Trusty, an extraordinary folk historian. He was the one who really pushed me. He said, 'Don't worry about what color you are. That's no reason why you shouldn't write the book.' "

Trusty, who died in 2004, was a longtime Atlantic City resident and informal archivist of black life in Atlantic City, particularly its entertainment scene. Trusty is quoted in the book.

According to one expert, the Northside's significance transcended its residents' importance to the white-run tourism industry of the 20th century. It was, offered Ralph Hunter Sr., founder and president of the African-American Heritage Museum of South Jersey in Newtonville, N.J., unique in the annals of black history in this country.

Borrowing Johnson's theme of the neighborhood as a "city-within-a-city," Hunter explained that the Northside was alone among black neighborhoods in northern cities because of the economic independence of its residents.

"They found a way to . . . keep all the money they earned on that side of town," he said, noting that black housekeepers or waiters who worked at one of the whites-only luxury hotels of the day could find everything they needed - from bars and barber shops to banks and credit unions - on the Northside.

The Northside also had an "extremely unique" feature that not even New York City's fabled Harlem could claim, said Hunter. "Harlem's homes were all rented out. In Atlantic City, there were homeowners."

Not that Atlantic City was a utopia for its black residents. As Johnson points out in the book, they were dependent on white business owners for much of their employment. And because the tourism season was brief, many blacks turned to the white establishment - notably Nucky Johnson, who consolidated his political power by taking care of black voters with handouts of food and money - to get through the long, cold off-season.

But when the warm weather returned, the Northside came to life, even for white tourists who would walk (or take a rolling chair inevitably pushed by a black man) to the Kentucky Avenue nightclub strip anchored by the legendary Club Harlem.

It was at "K-Y at the Curb" (as Northside residents called it) where the biggest African-American entertainers of the day made regular stops. Among the roster of immortals for whom the Northside was a second home were Count Basie, Redd Foxx, Sammy Davis Jr., Dinah Washington, Ray Charles and James Brown.

Thanks to Kentucky Avenue, said Johnson, "Atlantic City was probably the only place where large numbers of white people would sit side-by-side with black people and watch a show."

The Northside also delves into a mostly forgotten but seminal event in African-American history, the emergence of black political power at the 1964 Democratic National Convention at Convention Hall (now Boardwalk Hall), where Lyndon B. Johnson was nominated for a full term as president.

In the book, author Johnson tells how the arrival of black delegates and party movers and shakers empowered Northside residents to move away from the long-entrenched system of noblesse oblige on the part of white politicians.

More important, he writes of the intra-party battle between the overtly racist "official" delegation from Mississippi and the Mississippi Freedom Democratic Party, which unsuccessfully fought to have the official delegation denied seating at the convention.

Though the MFDP's quest failed, its high-profile agitation at the convention helped bolster the civil-rights movement.

Northside details the irony surrounding the area's eventual slide from thriving self-sufficiency into drug abuse, crime and searing poverty. As happened in other cities, the civil-rights campaigns of the 1950s and '60s designed to elevate the political, social and economic status of American blacks helped propel the Northside's decline.

"You had people who were educated and who made a decent living," said Johnson. "And once [integration] made it possible for those people to move out, they did just that. When the educated, successful professionals left the Northside, the bottom fell out, and it hasn't really recovered."

Emblematic of the neighborhood's issues was the Easter Sunday 1972 shootout between rival drug gangs inside Club Harlem. Five people died, and dozens were injured. The club stayed open until 1986, but its glory days were done.

The arrival of casinos in 1978 was supposed to spur redevelopment in what had become a depressed, inner-city neighborhood. But the neighborhood's still waiting.

Not that Johnson is convinced a Northside renaissance is out of the question.

"I don't have a way of predicting," he conceded, "but Atlantic City has been able to reinvent itself over and over again. Will it be able to reinvent itself again? Don't count it out."