Countries band together to promote trade, defend human rights, protect the environment and repel threats. They sign treaties and join international groups, and each time they do, they give up a bit of independence. That happened in a big way with the creation of the European Union, a free-trade zone and global political force forged from the fractious states of Europe. The question always was, could this extraordinary experiment hold together? Faced with the choice in a June 23 in-or-out referendum, the U.K. voted to leave the bloc it joined in 1973. The way many Brits saw it, the trade-offs they'd made to be part of the EU — notably control over immigration — no longer served their interests. They chose what's become known as Brexit.