If you are friends with a generally pro-marriage equality bunch, you probably saw your Facebook News Feed morph into a stream of red and white equals signs earlier this week as the Supreme Court heard two cases on the rights of gays to marry in this country. Was *everybody* seeing this, or was it just you and your liberal friends?

Facebook has dug into its data a bit and can give us some semblance of an answer: It wasn't just you; a ton of people changed their pics over to the Human Rights Campaign's equality sign (or some variation thereof) on Tuesday. It's impossible to get a precise number, but Facebook says that 2.7 million more U.S. Facebook users changed their profile picture that day than on the Tuesday before, a good stand-in for a null hypothesis. In general, the crop of people who changed their pictures this Tuesday as compared to last clustered around age 30, with roughly 3.5 percent of 30-year-old U.S. Facebook users taking part in the action.

Facebook's Data Science team also mapped out the likelihood of a profile-pic update across the nation, showing a pretttty widespread geographic distribution everywhere outside of the south and parts of the plains region. The county with the greatest participation rate? Washtenaw County, Michigan, where the University of Michigan has its main campus in Ann Arbor. Facebook estimates that 6.2 percent of users who logged in in Washtenaw Country changed their profile picture. In general, college towns saw high rates of participation (such as Orange and Durham counties in North Carolina, home of UNC and Duke, and Johnson County, Iowa, where the University of Iowa is based), as did major cities such as San Francisco, Los Angeles, New York City, and DC.

Facebook Data Science team rounded out their research with a closing remark. "For a long time, when people stood up for a cause and weren't all physically standing shoulder to shoulder, the size of their impact wasn't immediately apparent," they wrote. "But today, we can see the spread of an idea online in greater detail than ever before."