As shopkeepers are shuttering windows and flicking off the lights on any given night, thousands of families are boarding old rusty train cars that will carry them into this city for a long night's work.
Nearly 30,000 "cartoneros" invade the city's neon-laced streets every night pushing handmade canvas carts, overturning garbage cans, strewing trash along the streets and collecting materials that they sell to recycling centers - each on average earning 10 to 15 pesos, about the cost of a large pizza.
Once factory workers, farmers, or low-wage workers who lost jobs during Argentina's 2002 economic collapse, they were forced to invent work that scarcely existed here before the crisis. Unlike other South American metropolises that have seen generations of recyclers pass through their streets, this is a first for Buenos Aires. These people tend to be literate and have had other work experience.
When the economy dipped several years ago, Lidia Quinteros, a former shoemaker-turned-cartonero and activist, began boarding public trains with droves of others pushing carts piled high with plastic soda bottles, cardboard boxes, and paper scraps. When other passengers began to complain of the smell and the mess, cartoneros protested in front of government buildings, cutting off main thoroughfares - and winning special train service for their work.
Quinteros has been at the forefront of the cartonero movement, now a highly organized political movement that, in some ways, has changed the way Argentine society looks at waste management. The government, which registers a 12 percent unemployment rate, has recognized the economic and environmental benefits of informal recycling - huge savings on garbage collection and a 25 percent reduction of the city's solid waste going to landfills. Their work has been legalized and cartoneros receive a small subsidy for childcare.
Nearly half the cartonero population are children, and Quinteros began to see the negative effects on children working into the night and unable to focus in school. With a small subsidy from the government, she and several other mothers started a tutoring program for the children of recyclers.
Interviewed while stacking cardboard on her cart, Quinteros says: "When a crisis happens in your country, you'll have to do the same thing."