The Ku Klux Klan appears to be on the rise again after years of irrelevance and splintered obscurity.

"Due to the successful exploitation of hot-button issues," the Klan has seen "a surprising and troubling resurgence," states a new report by the Anti-Defamation League (ADL).

Gay marriage and urban crime are part of the picture. But, in particular, it is the debate over what to do about the nation's nearly 35 million immigrants, of whom about 11 million are in the US illegally, that has become the Klan's main recruiting tool.

"If any one single issue or trend can be credited with reenergizing the Klan, it is the debate over immigration in America," says Deborah Lauter, the ADL's civil rights director. "New groups [are] sprouting in parts of the country that have not seen much activity."

In addition to the South, where the Ku Klux Klan was founded by Confederate Civil War veterans in 1866, this now includes active or growing Klan chapters in Indiana, Michigan, Ohio, Iowa, Nebraska, Maryland, New Jersey, and Pennsylvania.

There is no centralized organization, and membership numbers are estimates at best – 5,000 to 8,000 in as many as 179 Klan groups, according to the ADL, a group that fights bigotry, especially anti-Semitism, and the Southern Poverty Law Center, a civil rights law firm and education center.

But it is the increase in activity, including rallies, recruitment drives, and distribution of racist literature, and the partnering with skinheads, neo-Nazis, and other kinds of hate groups, that civil rights groups find troubling.

As it did from its founding, the KKK views itself has having a religious dimension. Members see "lighting" a cross as a symbol of faith. Today, Christian Evangelicals are much more likely than mainstream Protestants or Roman Catholics to believe that "newcomers threaten traditional American customs and values," according to the Pew Research Center.

It is this trend in attitudes that the Klan hopes to use in recruiting new supporters among those opposed to US immigration policies and practices, according to Klan leaders and expert observers.

In a way, it's a reversion to the Klan's nativist origins.

"While we generally think of it as a white supremacist organization, the Klan at its peak was virulently anti-immigrant, particularly with regard to Catholic immigrants, Irish, and southern European," says Brian Levin, director of the Center for the Study of Hate and Extremism at California State University, San Bernardino.

That was in the 1920s, when the Klan numbered about 4.5 million. The KKK had dropped to an estimated 60,000 members during the civil rights era (1954-65) and had bottomed out at fewer than 2,000 members by the mid-1970s, says Mr. Levin, a civil rights attorney who teaches criminal justice.

Levin notes that any rise in KKK activity and membership today comes off a near-historic low, and "some of the chapters are rather slim pickings."

"I'm more worried about the exploitation of the immigration issue generally than I am about the Klan exploiting it," says Levin. "I think the Klan is going to hit a ceiling because of the negative symbolism, the negative baggage."

But, he adds, "The whole nature of hate group membership has changed with the advent of the Internet. You can take bits and pieces from whatever group you like without necessarily becoming a card- carrying member."

Although some KKK adherents still don robes and pointed hoods to hold rallies and burn crosses, younger followers are more likely to look like skinheads or neo-Nazis, decorated with racist tattoos and listening to white power rock bands such as Skrewdriver and Brutal Attack.

During the first half of this decade the number of hate groups in the US increased 33 percent to 803, according to the Southern Poverty Law Center. The Ku Klux Klan was an important part of that increase.