The number of U.S. families without the financial means to buy enough food rose last year, and those with children were hardest hit.

After several years of declines, the so-called national food hardship rate is climbing, according to findings from the Food Research & Action Center, a nonprofit group that works to eliminate hunger. The survey, based on a national Gallup poll of 338,000 households, found that nearly 16 percent of families lacked the funds to buy food at least once in 2017, up slightly from the previous year. The risk of hunger was 1.3 times higher in homes with kids.

"Often hidden behind closed doors, food hardship is a serious national problem that requires a serious national response," Jim Weill, president of the Food Research & Action Center, said in a statement. "Too many people in every region, state and community have been left behind in the economic recovery from the Great Recession and are still struggling to put food on the table."

Food Research & Action Center

By region, people living in the Southwest and Southeast struggled the most to put food on the table in 2017, with 19 percent and 17 percent households, respectively, occasionally lacking funds to buy groceries. Of the 10 states with the most hunger, four were in the Southeast and four in the Southwest.

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Mississippi residents had the highest food hardship rate -- more than a fifth of those surveyed reported they did not have enough money to buy food at some point in the last 12 months, the report shows.

In nearly half the states, at least one in seven households reported food hardship.

While the nation's unemployment rate continued to fall last year, inflation-adjusted wages were largely stagnant. That underscores the need for continued funding of programs such as the Supplement Nutrition Assistance Program, or SNAP, school meals and Medicaid, according to the Food Research & Action Center.