US income gap widened last year as top 1 percent gained most
Income inequality has been a rallying cry of the 2016 election, with more Americans turning fearful and angry about a shrinking middle class.
Donald Trump has pledged to restore prosperity by ripping up trade deals and using tariffs to return manufacturing jobs from overseas.
The tax data helps capture income inequality more fully than government surveys, which often fail to include the tiny fraction of ultra-rich Americans who play professional sports, star in Hollywood blockbusters, manage global corporations or trade successfully in the financial markets.