WASHINGTON (Reuters) - Some 37.9 million people -- one in eight Americans -- received food stamps to help buy food at latest count, the government said on Tuesday as enrollment set a record for the ninth month in a row.

Food stamps are the primary federal anti-hunger program. It helps poor people buy groceries. The economic stimulus package boosted benefits by $80 a month for a family of four.

Participation has surged since the financial-market turmoil more than a year ago and has set a record each month since December 2008. The Agriculture Department said enrollment reached 37.9 million in October, the latest month for which figures are available, up 746,000 from the previous month.

The average monthly benefit was $133.60 per person in October.

The Food Research and Action Center, an anti-hunger group, said enrollment of one in eight Americans is the highest share of the U.S. population ever in the program, which was renamed the Supplemental Nutrition Assistance Program in mid-2008.

(Reporting by Charles Abbott; Editing by Gary Hill)