Matt Drudge is not the only conservative to suggest that the presidency of Barack Obama has failed to quell or has even exacerbated racial tensions. "As a man raised in a post-racial America," commentator Steven Crowder tweeted, "I can say without a doubt, that Obama has made race relations the worst in my lifetime." Even television's Don Trump weighed in. And polling shows a majority of Americans think racial tensions have gotten worse under Obama.

After months of protests and outcry over the deaths of Michael Brown, Eric Garner, Tamir Rice, Walter Scott and, now, Freddie Gray in Baltimore, even impartial observers might wonder if something unique to Obama's tenure as president is inspiring more unrest. And the answer is yes — but it doesn't have anything to do with Obama.

If you are old enough, which I am, answer this question: Why did Los Angeles riot in 1992? There are any number of answers to that question, some of which share common characteristics with the tension that we've seen over the last 10 months. But distilled down, working backward to the cause, the trigger, the spark, the answer is obvious: The riots happened because of this.

That, of course, is Rodney King, being beaten by a group of Los Angeles police officers. When those officers were acquitted on assault charges following a trial held in the largely white Simi Valley, Los Angeles erupted into several days of riots that destroyed hundreds of buildings and left more than 50 dead. There were too many factors at play in the rioting to count -- tensions between police and the community, poverty and hopelessness among them -- but without that video, they would not have happened when they did.

It's easy now for me to embed that video via YouTube. It was much more difficult in 1992. Sometimes called America's first "viral video," it was handed over from an amateur photographer to a local news station, which ran it that night. It was picked up nationally and spread over traditional media outlets.

That is no longer how it works. Video of the shooting of Walter Scott in South Carolina was given to news outlets from an observer who was concerned about repercussions. But once it was published, it was seen within hours by what was certainly far more people than viewed the Rodney King beating that first night. The choking death of Eric Garner on Staten Island was filmed and posted online, where it helped propel his case to national attention. Michael Brown in Ferguson, Tamir Rice in Cleveland and Freddie Gray in Baltimore were all seen on videotape shot by surveillance systems or cell phone cameras shortly before their deaths, and the aftermath of the Brown shooting was taped by someone on the scene. The debate in each case was shaped by the video footage.

And shaped quickly. Social media is instantaneous. Twitter can be and has been used to inform, organize and inflame. Stories and photographs and videos created by people on the scene using the portable studios they carry in their pockets leap onto the Internet and spread in less time that it would have taken the man who filmed the Rodney King beating to rewind the video cassette.

These are innovations that happened largely while Barack Obama was president. Obama has been the first social media president and the first iPhone president. And that, far more than Obama's politics or his racial identity, has been why his second term has been heavy with unrest.

The first quarter in which Apple sold more than 2.5 million iPhones was the last quarter of 2008 -- when Obama was elected president. It hasn't sold below 3 million since. The popular Android smartphone didn't go on sale until that same quarter. It took months before cameras-in-pockets were ubiquitous, but they are now.

Social media was still so young in the 2008 election that it barely earned a mention in Pew's overview of online behavior during the campaign. Only about a quarter of people under the age of 30 got election information from "MySpace or Facebook." Now, more than 70 percent of all Americans use Facebook. Three times as many Americans used Twitter last year as in 2010; it's now used by almost a quarter of the country -- including many thought leaders and influential people in Washington.

Since Jan. 20, 2009, the day Barack Obama became president, the world of media and information sharing has changed dramatically, even if longstanding racial tensions have not. We're regularly seeing videos of (often black) people being shot by or struggling with (often white) police. The videos are sometimes from bystanders' cell phones, sometimes from police dashboard cameras (themselves a fairly recent development), sometimes from surveillance systems. And once they're online, they're everywhere. As with King, the unrest isn't happening because of the videos or stories. But the videos and stories are triggering action.

If John McCain had won election in 2008 and been reelected, it's hard to believe that Michael Brown, Eric Garner, Tamir Rice and Freddie Gray would still be alive. And it's hard to believe that their deaths wouldn't similarly have gained international attention. Both the problems that led to their deaths and the ad hoc media network that informed us about them would still exist.

Obama's America might not be post-racial, but it's definitely post-social.