Economists have analyzed the minimum wage and its effect on employment more often than almost any other topic. And the result of all this study is clear: Raising the minimum wage hurts the very people—low-skilled workers—that champions of the raise intend to help, because it prices many such workers out of jobs. That's just what a bill now under consideration by New Jersey's legislature will do. By raising the state minimum wage to $8.50 from $7.25 an hour, politicians will guarantee that fewer people get work.

The...