Gov. Gretchen Whitmer said Michigan parents starting back-to-school shopping should expect to pay more for backpacks and shoes as a result of President Donald Trump’s tariffs.

Many companies shipped more goods and raw materials into the U.S. before tariffs hit. Economists and analysts reckon that hoarding has helped some delay hiking prices until later in the year and explains why tariffs have not yet shown up in U.S. inflation data.

Adidas has warned that US tariffs will cost the German sportswear giant a further €200m (£173m) and confirmed that it will raise prices for American customers. Nearly half of the company's products are made in Asian countries which recently agreed trade deals with the US.