The black sports bra and matching leggings that Under Armour began selling Monday don’t look particularly distinctive from the rest of the workout attire on its website. But, in fact, the garments are different in a key way: They were made in the United States, marking a key milestone in the company’s ambitious bid to significantly rethink its manufacturing strategy. They are the first batch of clothing to be made at UA Lighthouse, a sprawling Under Armour facility that opened this summer in Baltimore. A 35,000-square-foot design and product development hub, it is an anchor of Under Armour’s attempt to figure out how to make clothing in the United States — an unusual venture in an industry where manufacturing has largely been done overseas for a generation. About 97 percent of clothing sold in the United States is imported, according to the American Apparel & Footwear Association. Just 2,000 of the garments are available for sale — 1,000 each of the bras and leggings — so it’s a small-scale start. But the process of creating them offers a look at what the future of Under Armour — and the wider apparel industry, for that matter — might look like. The company says that it was ...