"Should the United Kingdom remain a member of the European Union or leave the European Union?" In summer 2016, British citizens had to answer the question.
And 51.9 percent voted for a British exit. Brexit's economic fallout was immediate and ongoing; the pound dropped 10 percent right away. In the following years, the economy shrank by nearly 2 percent. Experts say the "Brexit" effect will keep compounding for now. Isolated Ireland could feel the worst of it, as could major trade partners like Germany.
So what happened? First, the feeling of a lack of control economically. A sense the European Union had failed to fix issues stemming from the 2008 financial crisis. The Eurozone still had record high unemployment of 12 percent in 2013.
The other part: U.K. citizens feeling a loss of cultural and national identity due to an influx of immigrants. A 2013 survey found 77 percent wanted less immigration.The EU prevents member countries from making certain decisions on their own, including immigration limits.
But this wasn't a perfectly partisan issue. Some key supporters of the "leave" campaign: Boris Johnson, former London mayor and conservative; and a leader of the other party, the Labour Party, Kate Hoey.
"Remain" voters said leaving the EU would be an economic disaster. Their argument: the U.K. and all member states benefit from open borders and the free movement of goods and people. It's one of the strongest economic areas of the world. Conservative Prime Minister David Cameron was firmly "remain."
But to satisfy supporters in 2013, he called for a renegotiation with the EU, then promised he would schedule a referendum on EU membership by the end of 2017. This pleased some people, but it was risky. When Cameron's Conservative Party, known as the Tories, won a majority in Parliament in 2015, he kept his promise.
The vote was scheduled for June 23, 2016. A record number of people registered to cast their ballot — more than 46 million. The results were unexpected. Prime Minister Cameron announced his resignation the next day.
