Josh Boak and Carrie Antlfinger at the Associated Press reported on a new study about generational earning this morning: With a median household income of $40,581, millennials earn 20 percent less than boomers did at the same stage of life, despite being better educated, according to a new analysis of Federal Reserve data by the advocacy group Young Invincibles. …Education does help boost incomes. But the median college-educated millennial with student debt is only earning slightly more than a baby boomer without a degree did in 1989. This is important stuff. When we talk about inequality, it’s important to remember that we’re not just talking about a disparity in earnings from the top one percent to the other 99 percent. We’re also talking about a disparity between generations, an income gap that grows over time. It is part of the reason why, though President Obama’s policies did begin to shrink the traditional measures of inequality (link PDF) , many Americans don’t feel as though the economy is improving. This report should serve as a warning to Democrats in the midterm elections and the 2020 presidential election: just because you’re not young enough to feel this inequality, you should understand that it exists. This is a big reason why Senator Bernie Sanders enjoyed the success that he did during the 2016 Democratic primary: he was speaking to a serious problem that most candidates, and most media outlets, didn’t even recognize was a problem. I realize that I’m not delivering some new insight here. Lots of people—including my colleagues at this here blog—have written extensively about student debt and other economic damages delivered exclusively onto millennials. But this new study is another solid piece of proof that inequality comes in a multitude of varieties, and Democrats need to be able to recognize and address all of them. The future of the party—and the future of this country—is at stake.