With the start of the second half of 2019, this expansion officially sets a new record as the longest growth cycle in modern U.S. history. However, growth has moderated lately. The U.S. Leading Economic Index (LEI) in May was unchanged from April. It's a dramatic pause after 10 years of strong growth.

"While the economic expansion is now entering its eleventh year, the longest in US history, the LEI clearly points to a moderation in growth towards 2% by year end," according to the economic team at The Conference Board, a big-business sponsored group that is responsible for tracking the monthly U.S. LEI.

From The Great Recession of 2008, which was the worst period of negative growth since The Great Depression, the current growth cycle began in April 2009, and GDP grew only modestly until 2015. Then, real wage gains began accelerating, propelling stronger than expected growth for over four years. Though U.S. growth recently leveled off, it's been a spectacular expansion, by modern historical standards.