The chart below depicts container traffic at the Port of Los Angeles, the largest volume US container port. Loaded inbound containers (blue), measured in twenty foot units or TEUs, have far exceeded loaded outbound units (red) for a number of years. What is noteworthy is that the ratio of loaded outbound to inbound containers has deteriorated from 48% to 38% over the last 6 years.
Imposition of tariffs has not reversed this. In fact the opposite. Stats for July 2019 show an 8.7% increase in inbound traffic and a 4.0% decrease in outbound traffic, while the ratio of inbound to outbound containers fell to a new low of 34%.