Even though the general election is more than 350 days away, the campaigns have already invested a lot of time and money into their digital marketing. Out of the field of 17 candidates, four candidates stood out this year with the best digital marketing strategies.

This is not a political endorsement of any candidate or their campaigns, simply a few observations looking through the lens of digital marketing and media.

Bernie Sanders

The Sanders campaign excels in its use of longform content. On Bernie Sanders' website, the issues tab has in-depth content on 16 issues central to Sanders' campaign. Well-written and informative, this content addresses these issues and provides concrete steps that Sanders would take to solve them. Sanders uses statistics to substantiate his claims, further boosting his credibility. His campaign team also created a page on the website that aggregates news stories relevant to Sanders' policies, called Democracy Daily. The content on this page is not generated by Sanders' team or even about him; instead, it focuses on the issues he cares about and provides easy social sharing options.

Carly Fiorina

The SuperPAC CARLY for America, which supports Carly Fiorina's candidacy, uses post-click marketing to engage voters. During the last two GOP debates, the team at CARLY for America used an interactive post-click campaign to create an engaging experience for users to voice their opinions. Once visitors arrived to the home page, they could enter the interactive experience and answer questions on Fiorina's policies, their intent to vote, and more. Once they finished the questions, they unlocked a free bumper sticker. This campaign collected valuable voter data while educating voters on Fiorina's stances. No one else in the field has used post-click marketing, and as a result these campaigns helped Fiorina stand out at critical times in the campaign.

Hillary Clinton

Clinton's use of social media is arguably the most effective out of all the candidates. She has a massive following: 4 million Twitter followers (the most out of all candidates), 1.1 million Facebook likes (the most out of the Democrats), and 217K Instagram followers (leading the Democrats and second to only Trump). She announced her campaign using YouTube and Twitter, and also has LinkedIn, Instagram, Facebook, Pinterest and Snapchat accounts. Clinton's Instagram account stands out - she uses trending hashtags like #tbt, she demonstrates a sense of humor in her posts, and she has let social influencers like Katy Perry take over her account for a day. Clinton also used Periscope to livestream campaign events and created a campaign-inspired Spotify playlist, showing that she's willing to embrace the newest social media marketing platforms.

Donald Trump

Trump has dominated news coverage ever since he announced he was running for president. His presence in mainstream news outlets has dramatically boosted his brand awareness as a candidate, and not just as a businessman and reality TV star. ROI on press is positive, and Trump has outpaced the other candidates from both parties in the press. As of the end of the summer, he had been mentioned 132,077 times in the press - almost 30,000 times more than Hillary Clinton and 62,420 more than Jeb Bush, the closest Republican at the time. When Trump hosted Saturday Night Live 9.3 million viewers tuned in - SNL's largest audience since 2013. Thus far, much of Trump's digital marketing efforts have cost his campaign nothing while propelling him forward in the polls.

From a collective online spend that's topping $1 billion, the one thing we know for certain is that the 2016 presidential election digital campaign is going down in the books.