The March on Washington aimed to secure a decent, livable wage for all Americans as a way to reduce income inequality. Fifty years later, that noble goal remains unachieved. In fact, the 1970s proved to be a turning point. The decades since show a steady decline in the share of national income going to the lower 50 percent and, indeed, to the lower 90 percent of American households.

The history of the federal minimum wage tells the same story. In real terms – adjusting the cash minimum wage for the actual prices its recipients have to pay – the real minimum wage rose significantly after the march from 1963 to 1968. However, it has mostly gone down since then. In terms of 2012 prices, the real minimum wage was worth $10.56 in 1968 but had dropped to $7.25 by 2012. The share of total after-tax U.S. income earned by the bottom 80 percent of households fell significantly from 1979 to 2007, according to the Congressional Budget Office.

The March on Washington demanded the opposite of what has mostly happened since. Besides earning a falling share of the national income, most Americans have and keep accumulating unsustainable debts. Increasingly desperate and with little success, they try to hold on to a standard of living their parents’ and grandparents’ generations fought for and won.

The economic goals of the 1963 March were denied by how the capitalist system has worked since then. In the time Dr. King had after the March, he came increasingly to understand that system as a key block to realizing his dream. That’s what brought him to Memphis.

No small irony attaches to the fact that by blocking realization of a decent, livable wage for all workers, the system generated its own deep crisis that began in 2007. That crisis endures for most Americans and makes them question the system more than at any time since the 1930s. It has cut so deep and lasted so long in good part because the mass of Americans earn too little, can no longer borrow much more, and can thus not spend enough to sustain the enterprises and jobs we need. At the same time, the richest 10 percent and the large corporations hoard unprecedented amounts that they do not invest because businesses lack sufficient consumer demand.

Dr. King grasped the contradiction. Capitalism drives and instructs employers to press down wages, yet doing so turns back and undermines the system with too few purchases. To secure a decent, livable wage requires more than getting employers to agree. It requires system change. Otherwise, the pressures of business, competition and all the rest of capitalism as a system will drive employers to reverse wage increases won in the past or simply resume their classic pressures on wages. The 1963 march and its demands were an important step, but the subsequent history teaches the additional steps we need to take.

Richard Wolff is a Professor of Economics Emeritus at the University of Massachusetts, Amherst, and Visiting Professor at the New School graduate program in International Affairs in New York. Wolff has published many books including Democracy at Work: A Cure for Capitalism, Occupy the Economy: Challenging Capitalism, and Capitalism Hits the Fan: The Global Economic Meltdown and What to Do About It, which was also made into a DVD. He appeared on Moyers & Company in March 2013.