Rep. Alexandria Ocasio-Cortez speaks about the Green New Deal in Washington, D.C., on May 13. She has shined a spotlight on a once-obscure brand of economics known as "modern monetary theory."
When the federal government spends more than it collects in taxes, which it does most years, it has to borrow money to make up the difference. That gap is the federal deficit, which is expected to top $1 trillion in 2019.
Treasury Building in Washington, D.C. The trend toward rising red ink was widely anticipated, given the GOP tax cuts and other government policies, including the president's demand for beefed-up military spending.
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