The economic downturn has decimated the market for recycled materials like cardboard, plastic, newspaper and metals. Across the country, this junk is accumulating by the ton in the yards and warehouses of recycling contractors, which are unable to find buyers or are unwilling to sell at rock-bottom prices.

Ordinarily the material would be turned into products like car parts, book covers and boxes for electronics. But with the slump in the scrap market, a trickle is starting to head for landfills instead of a second life.

“It’s awful,” said Briana Sternberg, education and outreach coordinator for Sedona Recycles, a nonprofit group in Arizona that recently stopped taking certain types of cardboard, like old cereal, rice and pasta boxes. There is no market for these, and the organization’s quarter-acre yard is already packed fence to fence.

“Either it goes to landfill or it begins to cost us money,” Ms. Sternberg said.

The collapse of the market is slowing the momentum of recycling overall, said Mark Arzoumanian, editor in chief of Official Board Markets. He said the problem would hurt individual recycling businesses, but also major retailers, like Wal-Mart Stores, that profit by selling refuse.