More and more Americans are buying used clothes from second-hand stores. Now, some major department stores have started selling old clothes, too. Recently, J.C. Penney and Macy’s started selling used clothing from ThredUP, an online thrift store. James Reinhart is co-founder and chief of ThredUP. He said of the partnerships, “You have to go where the customer is going.” The first big department store that entered the old clothes business was Neiman Marcus. In April, it received part ownership of Fashionphile, an online seller of used designer goods. And this fall, it will launch areas inside some of its stores where customers can sell old designer clothes directly to Fashionphile. These and other recent moves show how businesses can no longer ignore the growing preference of buying and selling old clothes. Shoppers want to pay less for clothes. And they would rather see their old clothes worn again than thrown away.