According to many news sources, including Mashable, the Election night for Obama vs Romney has become the most tweeted event of all time. Confirmed by Twitter Government (@gov):
With 20 million tweets, Election Day just became the most tweeted about event in US political history. #election2012
The retweets for Barack Obama winning the election, and also for spurring people to vote for him caused millions of tweets to occur throughout the night, and then all the other time zones added to that. A total: 20 million!
It will be a very long time until this is beaten. Millions more people will need to be active on Twitter, and perhaps it will be the next Presidential Debate in 4 years time, when Obama will be campaigning once again. The record was beaten by a huge amount, which makes it so hard to beat.