The U.S. Gross Domestic Product (GDP) is the sum total of all business activity in the U.S. Our economy is incredibly complex, but our GDP grows or declines based on two simple factors: (1) population changes, and (2) productivity changes.
Our population continues to grow, but our productivity has probably been in steep decline for nearly two decades. This is the result of a growing base of retirees as well as an alarming increase in younger people who are simply unemployable.
There's a reason why interest rates have remained at or near historic lows for years, folks.
Nonfarm business sector labor productivity increased 3.4 percent in the first quarter of 2019, the U.S. Bureau of Labor Statistics reported today, as output increased 3.9 percent and hours worked increased 0.5 percent.
https://www.bls.gov/news.release/pdf/prod2.pdf