The United States and China edged closer Tuesday to triggering the riskiest trade war in decades, a fight that could weaken the world's two largest economies, unsettle relations between Beijing and Washington and crimp global growth.
The collateral damage could be widespread.
If the tariffs the two countries have threatened to slap on each other's exports take effect, their consumers would have to pay higher retail prices. Companies would pay more for imported parts and would have to decide whether to absorb those higher costs — or pass them on to their customers.
American farmers could be evicted from a lucrative market for their goods. U.S. companies, from...