“I didn’t think we’d even be allowed to come here,” said Ms. Dreeszen, 41, glancing around at the shelves of fruit, whole-wheat pasta and baby food. “This is totally something that I never expected to happen, to have to resort to this.”

In Lake Forest, Ill., a wealthy Chicago suburb, a pantry in an Episcopal church that used to attract people from less affluent towns nearby has lately been flooded with people who have lost jobs. In Greenwich, Conn., a pantry organizer reported a “tremendous” increase in demand for food since December, with out-of-work landscapers and housekeepers as well as real estate professionals who have not made a sale in months filling the line.

And amid the million-dollar houses of Marin County in California, a pantry at the San Geronimo Valley Community Center last month changed its policy to allow people to stop by once a week instead of every other week, since there are so many new faces in line alongside the regulars. “We’re seeing people who work at banks, for software firms, for marketing firms, and they’re all losing their jobs,” said Dave Cort, the executive director. “Here we are in big, fancy Marin County, but we have people who are standing in line with their eyes wide open, thinking, ‘Oh, my God, I can’t believe I’m here.’ ”

The demand is not limited to pantries, which distribute groceries from food banks, supermarket surplus and individuals who donate through church or school can drives. The number of food-stamp recipients was up by 17 percent across New York State, and 12 percent in New Jersey, in November from a year before. When a mobile unit of the Essex County welfare office, as part of a pilot program to distribute food-stamp applications in other counties, stopped in Shop-Rite parking lots recently in Morris County, it was swamped.

“If one of our richest counties has people signing up for food stamps who have never signed up before, that indicates the depth of this problem with the lack of food,” said Kathleen DiChiara, executive director of Community FoodBank of New Jersey. “It’s the canary in the coal mine.”