For all their undying, cult-like support for him, has Donald Trump actually done anything for his base of voters?
Yes, if you were already doing well when the president was black.
The richest counties in America that supported Trump have seen their economic prospects increase over the past year, but the poorest counties that supported Trump have seen their prospects decline even further.
From the New York Times:
The most prosperous Trump-supporting counties — as ranked by the Economic Innovation Group, a think tank in Washington focused on geographic disparities in the American economy — added jobs at about a 2 percent annual rate in 2017. The least prosperous Trump counties, which the group calls “distressed,” did not add any new jobs, on net. As a group, the distressed counties saw more businesses close than open in 2017, and they lost population over the course of the year.
St. Charles County, which sits in the most prosperous slice of American counties, saw job growth of nearly 2 percent last year, and business growth of 6 percent. By contrast, about 200 miles north in Illinois, Knox County ranks in the bottom fifth of prosperity nationwide, according to the Economic Innovation Group’s rankings. It flipped in 2016 from supporting Mr. Obama, a Democrat, to Mr. Trump, a Republican.
There's no reason to think 2018 will look any different than 2017 when all is said and done. In fact, it may end up looking worse as Trump's trade war weighs down the economy across the board.
But there's also no reason to think this will change in 2019, or 2020, or any other year in the future unless states and the federal government pass new stimulus or sustained spending programs that give businesses a reason to operate in poor areas.
Trump said he was going to cover "everybody" with health care and pass a major infrastructure bill during the 2016 campaign and throughout most of 2017. Doing so may have actually reversed this trend, but if he wasn't outright lying then he certainly didn't have any idea what he was talking about.
Having failed to improve economic conditions for the kind of people who attend Trump's Nuremberg rallies, and in some cases even making things worse, it's self-evident and demonstrable that his war on immigrants and civil rights is all they truly care about. This isn't debatable.