The second quarter GDP number came in at 4.1%, a striking number so far into an economic recovery. Normally at this late stage of the economic cycle, with the recession of nine years ago, the economy would be softening not strengthening. The tax reform and reduction of restrictive regulation has to be given much of the credit.
It is also true that a 4% or higher number is not sustainable, but even if it dropped into the 3% range in the next two quarters that means we will have, for the first time since the recession, an annual growth rate of 3% or higher which is the U.S. long term normal rate.
Enjoy the ride while it lasts because all rides end at some point. The FED is likely the biggest culprit that will cut the ride short if they keep increasing interest rates.