There has been a long term deterioration in US Industrial production, as shown in the INDPRO index.
While monthly decreases happen all the time, a long-term decline in yearly production averages has been in place since September 2015.
When the yearly averages are placed on a graph and compared with US recessions since 1960, there is a clear correlation between long term industrial decline and recessions.
A decline in the yearly average can occur before a recession, or during a recession, as the graph below shows.
Note that I define a recession different to the NBER, but there is an overlap.
Here is how it appears on my spreadsheet: