"Directly … only about 5 percent of workers do get paid the minimum wage. And that comes to about 6.6 million workers, so it would not directly affect many," says Dr. Walden, an economist in the College of Agriculture and Life Sciences.

"But past experience shows that when the minimum wage goes up not only do those folks who receive minimum wage get a higher wage, but people just above them in the ranks in the ranks just above them may also get a higher … wage, because there is this ripple effect to the minimum wage," he adds. "And studies suggest, therefore, that perhaps another 6 percent of the workforce, or 8.3 million workers, might actually see a rise in their wage rates even though they are not getting the minimum wage because they are at that upper tier just above minimum wage workers.

"So altogether we might expect that about 11 percent, or around 15 million workers, would get the benefits of a higher minimum wage, either directly or indirectly," he concludes.