A campaign placard which reads "Vote Remain" hangs from a red public telephone box near Angel London Underground station in London, U.K., on Thursday, June 23, 2016. Britain began voting Thursday on whether to remain a member of the European Union or split from the 28-nation bloc, a once-in-a-generation decision that will determine the U.K.s future economic prosperity and the course of the EU. Photographer: Chris Ratcliffe/Bloomberg via Getty Images
