The baby boom is being evicted from the penthouse of American politics. And on the way out, it has decided to trash the place. That’s probably the best way to understand the generational implications of the tax legislation Republicans are driving through Congress. The House and Senate measures shower enormous benefits on households at the top of the economic ladder, a group that by all indications is older and whiter than the population overall. Then it hands the bill for those benefits largely to younger generations, who will pay through more federal debt; less spending on programs that could benefit them; and, eventually, higher taxes. In that way, the bills would intensify the generational inequity in how Washington allocates resources between the country’s increasingly diverse youthful generations and its predominantly white older population, groups I’ve called “the brown and the gray.” At a moment when political influence is inexorably shifting to the brown, the tax bill represents an 11th hour raid by the wealthiest of the gray. Republicans’ strength among older whites, particularly those without college degrees and outside major urban areas, has been central to the political gains that gave the GOP unified control of the White House and Congress—and the leverage to advance a tax bill. But the demographic foundation of that political dominance is eroding. The baby-boom generation, which has voted reliably Republican in recent years, has been the largest generation of eligible voters since 1978. But in 2018, for the first time, slightly more Millennials than baby boomers will be eligible to vote, according to forecasts from the Center for American Progress’s States of Change project. Higher turnout rates among baby boomers will preserve their advantage among actual voters for a while. But sometime around 2024, Millennials will likely surpass them. The post-Millennials, Americans born after 2000 who’ll enter the electorate starting in 2020, will widen the advantage. This generational shift will trigger a profound racial change: While about 80 percent of the baby boom is white, over two-fifths of Millennials and nearly half of the post-Millennials are not.