Washington is girding for another debate over raising the federal minimum wage, which has stood at $7.25 an hour since 2009. Many Democrats in Congress – led by Rep. George Miller of California in the House and Sen. Tom Harkin of Iowa in the Senate – want to raise that $7.25 amount (actually, $4.87 in 1996 dollars) to $10.10 an hour. They also want to raise the minimum wage for those paid in tips as well as wages – frozen at $2.13 an hour since 1991 – to 70 percent of the standard minimum wage. Meanwhile, those states which have...