Updated on June 22 at 6:56 a.m. ET
The British are voting Thursday in a historic referendum on EU membership, a vote that could have implications not only for the U.K. but for the entire 28-member bloc that represents Europe’s most ambitious post-World War II experiment as well as one of the world’s largest economies.
Initial figures from the country’s Electoral Commission said 46,499,537 people had registered—a record in Britain for what is only its third referendum ever. Polls opened at 7 a.m. local time (3 a.m. ET) and will close at 10 p.m. local time (5 p.m. ET). Under electoral rules, British media can only report on certain aspects of Thursday’s vote, but the results will begin to emerge once the polls close.
Opinion polls conducted ahead of the referendum showed a statistical dead heat.
The intensity of debate is clear in recent remarks from U.K. politicians on opposing sides of the debate, who have invoked not only that exemplar of high-intensity rhetoric, Hitler (on behalf of the “leave” side), but his murderous, present-day ideological descendant, ISIS “caliph” Abu Bakr al-Baghdadi (in defense of staying).
There have been dire warnings about the consequences, economic and otherwise, of leaving the EU, pleas for the U.K. to remain, and impassioned arguments as well as practical ones for it to get out. But what exactly is at issue and who is saying what? What follows is an updating guide to the state of the debate ahead of the June 23 vote.