By NINA BERNSTEIN After the four suicide bombers in London were identified last week, news accounts focused on life in the old mill town of Leeds, where they grew up: the immigrant enclaves, the high unemployment, the rising anger and alienation of Muslim residents. Some Britons grasping for an explanation pointed at those conditions, however tentative their link to homegrown terrorism. Mahendra Kumar Patel, the manager of Patel’s Cash and Carry in Jersey City, has immigrants of many ethnic groups as customers. That rough sketch of Leeds had a familiar ring for many residents of the Northeastern United States, where old mill towns in New Jersey and upstate New York have also drawn many immigrants to faded neighborhoods teetering between blight and renewal. Three of the suspects were raised in immigrant families from Pakistan and one from Jamaica. New York, New Jersey and Connecticut are now home to at least 20 percent of the nation’s 219,000 Pakistani immigrants, and more than half of the 513,000 immigrants from Jamaica. But the differences between the suspects’ hometown and the depressed cities around New York are actually stronger than the similarities. Social conditions among British immigrants, for example, appear to be considerably worse than they are in the United States. The 747,000 Pakistanis in Britain, counted among its nonwhite residents, are three times more likely to be out of work than white Britons, according to one of several bleak statistics showcased in the 2001 British census. Forty percent of Pakistani women and 28 percent of Pakistani men are listed as having no job qualifications, and school failure among Caribbean blacks is triple the rate for white Britons, who constitute 92 percent of the population. In America, where few surveys even break out ethnic origins, a much rosier picture emerges from available figures. Pakistani household incomes in New York are close to the $43,393 median and exceed it in New Jersey – $56,566 compared with $55,145, according to 1999 figures, the most recent available. Jamaicans fare a little less well statewide, but have robust rates of household income and educational success in New York City, where they are concentrated. They have a clear edge: English proficiency in a place where one in four residents cannot speak it well, and where nearly half of the work force is foreign-born. While South Asian immigrants to Britain began arriving soon after World War II, they were part of a stream of temporary workers to a small, culturally homogenous country where they remained outsiders. In the United States, the pioneer immigrants from predominantly Muslim lands arrived mainly after 1980, many as university students, and like Caribbean blacks, entered a diverse country built on immigration. But demographics fall short of explaining terrorism. As details emerged about the British suspects’ relatively prosperous lives, experts and immigrant parents alike wondered how much collective benchmarks mean in predicting the extremism of a handful of angry people. Compared with Britain, “We definitely have a different dynamic going on here in the United States,” said Peter Skerry, a political scientist at Boston College. “I don’t know that that necessarily means we’re out of the woods – it doesn’t take very much for a set of individuals to adopt attitudes that could lead to a terrorist act.” Others, like Steven Camarota, director of research at the Center of Immigration Studies, which favors more restriction on immigration, point out that this important demographic difference is temporary: Since most immigrants to the United States from Muslim countries arrived after 1990, few of the children born to them here have reached adulthood yet. He found that more than 85 percent of the 100,000 children born in America to Pakistanis and Bangladeshis are under 20. In a Jersey City shop where fresh goat meat and comic videos in Urdu compete for shelf space, Zafar Zafar, a Pakistani father of three, echoed such concerns last week. Mr. Zafar, whose oldest child is 13, struggled in imperfect English to convey his horror at the case of Shahzad Tanweer, 22, the suspect described as a pious but fun-loving youth whose father owned a fish-and-chips shop in Leeds.