A coalition of unions and nonprofit groups staged rallies at Wal-Mart stores in 100 cities in 40 states to protest labor practices at the nation’s largest retailer.

“Behind that smiley face is a single mother who makes $7.50 an hour and can’t afford health insurance for her family because Wal-Mart charges her $400 a month for it,” said Rian Wathen of United Food & Commercial Workers Local 700 in Indianapolis.

In Columbia, S.C., protesters stood near a highway holding signs bearing phrases like “living wages” and “affordable health care.”

“It’s the great American company, but are they representing American values?” said Donna Dewitt, head of the South Carolina AFL-CIO. “It’s not the company that Sam Walton founded.”

Walton, who founded Wal-Mart in Arkansas in 1962, died 10 years ago.

Wal-Mart now has more than 1.3 million employees. The company says it offers unrivaled career opportunities and treats workers well.

“We make sure to offer competitive wages and benefits, including health care, in every market we are in,” spokeswoman Mona Williams said.

Wal-Mart spokesman Bill Wertz said the workers are nonunion by choice, but organizers say the company keeps out unions by intimidation.

Thirty-one National Labor Relations Board cases involving Wal-Mart are pending before administrative law judges, NLRB spokesman David Parker said.

Wal-Mart also is fighting state and federal lawsuits filed by workers who accuse the company of forcing them to work hours off the clock.

More than 400 employees from 24 of Wal-Mart’s 27 Oregon stores are involved in a class-action lawsuit in court now that alleges the retailer cheated employees out of overtime pay. On Thursday, dozens of protesters were outside a Portland Wal-Mart.