READING, Pa. — The exhausted mothers who come to the Second Street Learning Center here — a day care provider for mostly low-income families — speak of low wages, hard jobs and an economy gone bad.

Ashley Kelleher supports her family on the $900 a month she earns as a waitress at an International House of Pancakes. Louri Williams packs cakes and pies all night for $8 an hour, takes morning classes, and picks up her children in the afternoon. Teresa Santiago takes complaints from building supply customers for $10 an hour, not enough to cover her $1,900 in monthly bills.

These are common stories in Reading, a struggling city of 88,000 that has earned the unwelcome distinction of having the largest share of its residents living in poverty, barely edging out Flint, Mich., according to new Census Bureau data. The count includes only cities with populations of 65,000 or more, and has a margin of error that makes it difficult to declare a winner — or, perhaps more to the point, a loser.

Reading began the last decade at No. 32. But it broke into the top 10 in 2007, joining other places known for their high rates of poverty like Flint, Camden, N.J., and Brownsville, Tex., according to an analysis of the data for The New York Times by Andrew A. Beveridge, a demographer at Queens College.