The city council in Washington, D.C., has approved a measure that would force large retailers to pay workers a living wage of at least $12.50 an hour. The vote came in defiance of a threat from the world’s largest retailer, Wal-Mart, which says it will cancel plans to build three new stores in the D.C. area. The living wage rule applies to so-called “big box” retailers, with stores of at least 75,000 square feet and annual revenues of at least $1 billion. The bill excludes existing businesses and stores with unionized workplaces. Mayor Vincent Gray has yet to disclose whether or not he will issue a veto. He faces heavy pressure from Wal-Mart and other major retailers. In addition to canceling plans for three stores, Wal-Mart has said it will consider scrapping another three already under construction.