Brexit referendum

On June 23, 2016, UK voters chose to leave the European Union by a margin of 52% to 48%, prompting the resignation of Prime Minister David Cameron and beginning more than four years of negotiations over the terms of departure. The pound fell to a 31-year low against the dollar the day after the vote, and the years of uncertainty over the eventual trading relationship are estimated by several studies to have measurably reduced UK business investment even before formal withdrawal. The UK left the EU on January 31, 2020, and the transition period ended on December 31, 2020, when a new EU-UK Trade and Cooperation Agreement took effect, restoring tariff-free goods trade but adding customs and regulatory friction that had not existed under single-market membership.