Kara Alaimo is an assistant professor of public relations at Hofstra University. She previously served in the Obama administration as spokeswoman for international affairs in the Treasury Department. Follow her on Twitter @karaalaimo The opinions expressed in this commentary are solely those of the author.

(CNN) Donald Trump's candidacy was not taken seriously by the mainstream media and even the establishment of his own party, but his strategic use of social media propelled him to the presidency.

And while it may appear healthy for our political system that social media gives opportunities to people like him — who are, for example, less politically connected -- to speak to the American people, the way social platforms were actually used in this election cycle is deeply dangerous for our democracy.

To see how we've come to this point, it's useful to look at the past few presidential campaigns.

Indeed, although Donald Trump may appear to be the antithesis of Barack Obama, the last two men elected President of the United States are strikingly similar on two scores: both were anti-establishment candidates who won the presidency largely by outsmarting their opponents on social media.

Trump, who a ccording to Reuters tweeted more than any other candidate in the presidential race, amassed 4 million more followers on Twitter than Hillary Clinton and 5 million more on Facebook. With Trump's supporters enthusiastically liking and sharing his content, he created what Mike Berland, CEO of the market research firm Edelman Berland, called "a continuous Trump rally that happens on Twitter at all hours."

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The social media company SocialFlow calculated during the campaign that Trump was getting more than three times more free exposure on social media than Clinton. The company found that, by January, he had become "the most talked-about person on the planet."

Last year, in an interview with New York Times reporter Michael Barbaro (between breaks to check Twitter), Trump said that before social media, his only option was to sue his rivals. But with the modern ability to argue on social platforms, he felt he had "more power than they do."

In his first interview as President-elect, the famously wealth-obsessed businessman reported that he believed social media is more powerful than money. "The fact that I have such power in terms of numbers with Facebook, Twitter, Instagram, etc., I think it helped me win all of these races where they're spending much more money than I spent," Trump said. (His campaign spent about half as much as Clinton's). Trump also appreciated the ability to bypass the filter of the traditional media and speak directly to citizens via social media, describing his large Twitter following (in a tweet) as "like having your own newspaper."

Like Trump, Obama started as an outsider candidate whose unlikely rise was fueled by the savvy use of social media, suggesting the beginnings of a pattern. In 2008 , Barack Obama had 112,474 Twitter followers, while John McCain had a mere 4,603. On the then-more popular platform Facebook, Obama had 2,379,102 supporters, compared to McCain's 620,359. ( Past studies have also found that opposition politicians in Congress tend to use social media more than their counterparts, "as an instrument for voicing dissent directly to the public.")

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If social media serves to broaden the pool of potential politicians by allowing candidates to get their ideas to the American people -- and to run less expensive campaigns -- how has it damaged the country?

Three major ways:

First, and most obviously, social media (literally) cut our national discourse short. Kerric Harvey, author of the Encyclopedia of Social Media and Politics, said Twitter "makes it so that what ought to be a conversation is just a set of Post-it notes that are scattered."

This helps explain why a candidate who had never before discussed policy was able to win the election. In fact, in his interview with Barbaro of the Times , Trump said he only wished that Twitter's 140 character limit was longer "on 10% of the occasions." The words most frequently used by Trump in his tweets were "great," "winner" or "winners," and "loser" or "losers."

The social media tracking company Brandwatch found that Trump and Clinton's 10 most tweeted days (with the exception of conversations around the presidential debates) included just two conversations about policy.

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Second, social media is fueling the so-called "post-truth" era in American politics because it allows candidates to bypass traditional fact checkers -- reporters and debate moderators -- to communicate directly with the American people. According to PolitiFact, just 14% of Donald Trump's statements have been true. Fake accounts then amplified Trump's (sometimes inaccurate) tweets. The website Twitter Audit f ound that 39% of Trump's Twitter followers -- compared with just 5% of Clinton's -- were computer generated bots.

Another problem is that fake news stories have proliferated on social media. According to Buzzfeed , people in the town of Veles, Macedonia, developed a cottage industry over the past year, creating at least 140 fake news sites that spread pro-Trump stories across social media platforms. Zeynep Tufekci, associate professor of information and library science at the University of North Carolina, noted that a single false story purporting that Pope Francis had endorsed Trump was likely viewed by tens of millions of people on Facebook.

Third, social media is deepening the divide among more conservative and liberal Americans. Eli Pariser has noted that social media users now live in a "filter bubble" in which social platforms tailor the content we see to our interests, leaving us unexposed to other points of view (the divide is so stark that this year the Wall Street Journal created an interactive to show Americans what the Facebook feeds of the other side actually look like.)

New York Post columnist Johnny Oleksinski argued recently that this explained why Clinton supporters were so shocked by the results of the election, because "neither America believes the other really exists. Because it's nowhere to be found on its Facebook news feed." Too often people fail to engage in productive conversations with friends on Facebook who have differing views, likely because discourse on social media has become so vitriolic. A Pew study released last month found that 84% of social media users somewhat or very much agree that "people say things when discussing politics on social media that they would never say in person."

It doesn't have to be this way. Citizens could demand that politicians use social media more substantively and truthfully -- and tweet back to call them out when they don't. Social media executives could better police false content (Facebook and Google both announced actions to combat false news this week). And we can all try to engage constructively with people of a wide range of beliefs to debate the issues of the day.

There is reason to think this can work. One study found that if social media users see that a lot of people recommend a particular story, they will click on it even if the news source is partisan and not in line with their beliefs. This suggests that there is still room for dialogue between people with red and blue feeds.