LOS ANGELES — Among boisterous vendors hawking ice cream, hot dogs and assorted wares from carts in the heart of Los Angeles, an illicit business quietly caters to undocumented immigrants eager to work in the United States. Its purveyors softly call out, “Mica, mica,” Spanish slang for the laminated cards they are offering to potential clients.

“What do you need?” asked a woman on a crowded sidewalk facing MacArthur Park, the epicenter of the trade, clutching a notebook in which she prepared to jot down an order. “She can get you anything fast,” added a man who was with her.

A set of documents — a Social Security card and a green card — can be obtained for $80 to $200, depending on the customer’s bargaining power and the quality of the forgery. The fakes are a worthwhile investment for undocumented immigrants, opening the possibility of employment at a restaurant, hotel and many other establishments in the country’s second-largest city and beyond.

The failure by Congress to agree on new immigration legislation or viable guest worker programs to meet the demands of the United States economy has ensured the survival of the counterfeit identification industry, which sprouted after lawmakers last passed immigration reform, in 1986. The Immigration Reform and Control Act legalized undocumented immigrants in the country since 1982 and also prohibited employers from hiring unauthorized workers.