No one knows how long the current economic expansion will continue.
But some seven years after the last recession ended, economists are keeping an eagle eye on the latest data looking for signs that another downturn may be approaching.
For now, much of the economic data is pointing to continued, if somewhat weak, growth. Companies are hiring, wages are rising slowly and consumers are spending.
But belt-tightening by businesses on investment in new equipment and buildings could be a sign of a deeper slowdown ahead, according to economists at Credit Suisse.
"Extended periods of falling real business investment are strongly associated with US recessions," they wrote in a note to clients. "That's why the recent three consecutive quarters of contraction are concerning."