After decades of earnest public-information campaigns, Americans are finally recycling. Airports, malls, schools, and office buildings across the country have bins for plastic bottles and aluminum cans and newspapers. In some cities, you can be fined if inspectors discover that you haven’t recycled appropriately. But now much of that carefully sorted recycling is ending up in the trash. For decades, we were sending the bulk of our recycling to China — tons and tons of it, sent over on ships to be made into goods such as shoes and bags and new plastic products. But last year, the country restricted...