Feb. 21 (Bloomberg) — In 1914, Henry Ford announced he was more than doubling the average wage of Ford Motor Co. factory workers to $5 a day, in part so they could afford a Model T. His act took the world by surprise, spurred auto sales and helped create an American middle class.

One hundred years later, U.S. companies including Gap Inc. and Wal-Mart Stores Inc. are caught up in the debate over raising pay — this time an increase in the federal minimum wage. President Barack Obama and Senate Democrats want to raise it to $10.10 an hour from $7.25, saying doing so will bolster the economy and reduce income inequality. House Republicans and industry groups oppose the plan, deeming it a job killer.

"When Henry Ford announced the 5-dollar-day, the response was that it would diminish the auto industry and bankrupt his company," Harley Shaiken, a labor economist at the University of California, Berkeley, said in an interview. "Instead it jump-started purchasing power, reduced turnover and increased the profitability of Ford Motor Co. There's a lesson we can still learn from that."