Cardboard-box demand is slumping, flashing a potential warning about the health of the American consumer given that goods ranging from pizzas to ovens are transported in corrugated packaging. A historic run of pulp-mill closures is also signaling problems for the companies that make corrugated packaging as well as the timberland owners who sell them wood. International Paper, the country’s biggest box maker, announced last month the shutdown of two US containerboard mills, which make the brown paper that is folded into corrugated packaging. …It is a surprising turn in the e-commerce era. Box makers and analysts say demand presently suffers from uncertainty in US boardrooms and export markets because of President Trump’s tariffs as well as from weakening consumer spending. The sputtering housing market has also hurt, reducing the need for moving boxes as well as packaging for building products and appliances. [to access the full story a WSJ subscription is required]