In 2008 I posted a photo of myself holding my filled-in write-in ballot next to a cardboard cutout of Obama. I thought it was a little amusing, and I had made no secret of who I was voting for. But I got chided via social media, for what seems to me to be a good reason: we wouldn’t want the posting of ballot photos to become a common practice since it could lead to social pressure on people who don’t want their actual vote to be known. Imagine, say, a coal mine owner who is pressuring employees to vote for a particular candidate, and who puts up a “voluntary” “Post your Ballot Photo!” page. An employee might assume that a failure to post would be taken as a vote for the “wrong” candidate, and thus would be in a difficult position.
Now, that’s a hypothetical of course, but it captures a reason to preserve the norm that actual ballots are private, not public. Brag all you want about who you voted for — please! — but I think it’s a good idea to keep your actual ballot secret.
On the other hand, if you posted your ballot, it’s not something I find publicly chide-worthy.
(PS: I voted for President Obama. Quelle surprise!)