Retail Sales Come Out Tomorrow, But Box Sales Are Already Here

Analysts and investors will scour Friday’s retail sales report for a readout on how US households are feeling about the economy. Those watching the cardboard box industry say they already have an idea.

A nontraditional economic indicator, sales of the corrugated cardboard used to make the boxes that transport everything from doughnuts to dishwashers are slumping, signaling that retail demand across industries may be due for its own correction in the not-too-distant future.

US box shipments—that is, volumes of empty packaging materials sold to retailers, which in turn use them to ship orders to warehouses, storefronts and Americans’ doorsteps—fell to ...