A sizable number of the recipients of federal aid programs such as Medicaid and food stamps are employed by some of the biggest and more profitable companies in the United States, chief among them Walmart and McDonald's. "Wages at the bottom and middle of the income spectrum have been essentially flat since the late 1970s," said Ken Jacobs, chairman of U.C. Berkeley's Labor Center and a co-author of two Berkeley reports on the topic. "As productivity has increased, pay has stayed very low, and again, our federal minimum wage is well below where it would have been if it kept up with inflation and very far where it would have been if it kept up with productivity growth. So many families earn too little to get by on what they earn from their jobs."