Minimum Wages and Employment: A Review of Evidence From New Minimum Wage Research

National Bureau of Economic Research has the evidence: the demand for labor is a downward sloping curve. The Chicago Tribune reports:

a widely cited 2006 study by David Neumark, an economics professor at the University of California at Irvine, and William Wascher, deputy director of research and statistics at the Board of Governors of the Federal Reserve System, examined the literature on this issue and found "the weight of the evidence points to disemployment effects."

It also found that "minimum wages may harm the least skilled workers more than is suggested by the net disemployment effects estimated in many studies."

A lot of "progressives" aren't big on scientific evidence.