UC Berkeley released their study of low wage workers' pay, adjusted for inflation,
over the past 35 years.
Berkeley researchers analyzing U.S. Census Bureau data at the campus’s Center for Labor Research and Education found that low-wage workers, defined as those earning hourly wages of $13.63 or less, have seen steady declines in their inflation-adjusted buying power. This low-wage workforce, nearly three-quarters nonwhite and concentrated in two industries — retail trade, and restaurants and other food services — has also become older and more highly educated.
Teens made up 5 percent of low-wage workers in 2014, down from 16 percent in 1979, and 48 percent of low-wage earners in 2014 had attended some college, compared to 39 percent in 1979. The analysis also showed that 40 percent of the state’s low-wage workers in 2014 were foreign-born.
Low wage workers are older and more educated than their 1970s counterparts. The gap between the top one percent and the lowest economic rung on the ladder grows, not simply because the rich get richer—it's because they pay into our system less and less.
You can see the work they did published here.