Nearly a third of the nation’s working families earn salaries so low that they struggle to pay for their necessities, according to a new report.

The ranks of the so-called working poor have grown even as the nation has created new jobs for 27 consecutive months and is showing other signs of shaking off the worst effects of the recession.

“Although many people are returning to work, they are often taking jobs with lower wages and less job security, compared with the middle class jobs they held before the downturn,” according to a report released Tuesday by the Working Poor Families Project, a national initiative aimed at fostering state policies to help low-income working families.