Over the last week, many Facebook users have shown support for marriage equality as two high-profile cases get underway at the US Supreme Court. They've done so in a simple yet instantly noticeable way; by substituting their usual profile photo for a pink-on-red equal sign designed by the Human Rights Campaign. By now many of you have likely seen the symbol dominating your News Feed, and Facebook is chiming in with some hard numbers on just how widespread the movement has become. Facebook says that on March 26th, roughly 2.7 million more people updated their profile photo compared with the week prior — an increase of 120 percent." That means a total of about four million users out of an estimated 160 to 180 million users in the US changed their profile pictures last Tuesday. As the graphic below shows, this uptick in swapped profile photos went hand-in-hand with the kickoff of HRC's campaign.

Facebook also broke down results by age, according to Eytan Bakshy (who works on the social network's data science team). "Those closest to 30 years old showed the greatest increase in updating," he said, estimating that around 3.5 percent of 30-year-olds updated their profiles in direct response to the same-sex campaign. And finally, the company's researchers wanted to see how the numbers panned out geographically. For this overview, they looked at the entire country county-by-county. College neighborhoods showed the biggest jump in profile changes, with the trend extending to San Francisco, Washington DC, and elsewhere.

"Today, we can see the spread of an idea online in greater detail than ever before."

Like many businesses in Silicon Valley, Facebook has been a longtime advocate of equal rights for same-sex couples. And beyond the social cause the movement speaks to, it's yet another demonstration of Facebook's wide reach. "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," writes Bakshy. "But today, we can see the spread of an idea online in greater detail than ever before."