After waiting in line two hours and 45 minutes, huddled with other immigrants against the cold, a freezing Giovanni Gusita was just short of entering the application support center of the U.S. Citizenship and Immigration Services in Jackson Heights, Queens. “In summertime you don’t mind, but in this weather it’s something else,” Mr. Gusita, a 36-year-old immigrant from Italy, said. “This treatment is so bad.”

Since the attacks of September 11, 2001, the Department of Homeland Security has stepped up background checks and requirements for biometric information such as fingerprints and photographs on applications for permanent residency, work authorization, and temporary protective status. As local application processing has picked up recently, the Jackson Heights center has been hit hard.

Earlier this week, on a day when temperatures dropped well below freezing, immigrants from India, Ecuador, China, Egypt, and elsewhere shivered in a line that extended a block and a half from the entrance to the small building housing the center on Roosevelt Avenue. Clutching immigration documents, some jumped back and forth on frozen toes in an effort to prevent frostbite. Others wrapped their faces tightly in scarves to stop their teeth from chattering.

Tears caused by the cold dripped from Juana Merchan’s tired eyes. “It’s incredible, I can’t even feel my fingers,” Ms. Merchan, a 53-year-old immigrant from Ecuador, said in Spanish. “I had no idea that we’d have to wait. I would have brought more coats, more gloves,” Ms. Merchan, in line with her 16-year-old son to renew her permanent residency, said.

After waiting nearly three hours, she arrived inside a small, warm waiting room and joined about four dozen other immigrants. The security guard, who said this was a daily occurrence, had admitted the elderly, disabled, and infants. Meanwhile, he was forced to fend off a continuous stream of immigrants with appointments. When he told them that they would now have to spend hours outside in the cold, they looked at him with disbelief.

A spokesman for U.S. Citizenship and Immigration Services, Shawn Saucier, said the reason for the lines is simple: “We’re a victim of our own success.” Last year, New York brought in experienced adjudication officers and new part-time staff to try to chip away at the backlog of application processing, which is the longest in the country. The city’s immigration service is now processing green card applications submitted three years ago. “We’ve had very aggressive backlog elimination efforts in the New York district right now, and part of the result of that is that we need to use the application support centers more and more,” Mr. Saucier said.

A chair of the New York State bar association’s immigration and nationality committee, Matthew Dunn, said it’s true the overall processing has improved, likely contributing to the long lines in the cold. But delays, he said, are just part of a complex web of problems in handling applications.

“I don’t know in any other sector where the service would be accepted,” Mr. Dunn, a former attorney for the Immigration and Naturalization Services, said. “But having said that, I still think the immigration service is trying with the resources they have. For years, especially the New York district has been pleading for more money.”

While the city’s five other centers have also reported increased traffic, Mr. Saucier said the Jackson Heights center is the worst because the capacity is so small. To try to alleviate the problem, he said the agency has taken steps to redistribute the clients or enlarge the facility. Still, those in line were not convinced there would be any solution in the Queens neighborhood.

“It depends on how much they can get away with,” said Luz Duran, 32, who had accompanied her mother, an immigrant from the Dominican Republic, to renew her green card application. “I don’t think in Manhattan or any other high-income neighborhood they would have people waiting outside in the cold.”