Two years ago, on the morning of the 2012 election in the United States, I got an email with an urgent subject line: "You should write the story of how Facebook blew an opportunity to turn out 300k voters." The sender, a veteran progressive online activist who would prefer to remain anonymous, was upset for good reason. The election was bound to be close, and as of 10am that morning he hadn't yet seen an "I'm Voting" button on his Facebook page, nor had another colleague of his. Nor was one on my own Facebook page. Given that when Facebook deployed a similar "I Voted" button in 2010, and added messages in users' News Feeds showing them the names and faces...