Looking back on the 2012 election, young voters proved to be even more crucial to President Obama’s winning coalition than in 2008.

Voters between the ages of 18 and 29 made up 19 percent of the electorate, up from 18 percent in 2008, and 17 percent in 2004.

Moreover, a study done by the Center for Information and Research on Civic Learning and Engagement (CIRCLE) determined that if no one under the age of 30 had voted, the electoral votes of Ohio, Pennsylvania, Virginia and Florida, and therefore the Electoral College, would have swung to Romney.

In 2008, the youth vote was decisive in three states: Indiana, Virginia and North Carolina.

But 2012 wasn’t supposed to play out this way.

2012 was supposed to be the year where young people stayed in their dorm rooms and parents’ basements, gripped by the apathy that they were supposed to feel after being deprived of hope and change for four years. Conventional wisdom held that fewer young people would come out to vote this year, and many who did would jump ship and vote for Mitt Romney, genie of the job market.

It was a great story, and a terrible prediction. But what happened – why did young voters come through for Obama again?

Some have attributed President Obama’s success with young voters to policies such as student loan reform and increased access to contraception. However, students getting “gifts” from the Obama administration explains his win among young people about as well as the auto bailout explains his win in Ohio (it doesn’t, certainly not fully). Research has shown that, unless they are of high salience to the voter, policies tend to be lagging, rather than leading, indicators of support.

This means that while the President did make college affordability a major talking point on the trail, his student loan reform program was only likely to swing the votes of a) college students or recent college graduates who b) directly benefited from the program and c) weren’t already planning on supporting him.

Demographics aren’t everything, but they go much farther in explaining President Obama’s success; his win among young voters was indicative of the changing makeup of the American electorate.

Only 62 percent of young voters in 2012 identified as white, compared with 72 percent nationally. Sixty percent of 18-29 year olds have some level of college experience; 47 percent of the nation as a whole reports having at least some higher education. A slice of the electorate that is more racially diverse and more educated will tend to be more liberal and Democratic-leaning than the country as a whole.

Finally, campaigns matter, and 2012 was no exception.

Obama’s 59 percent share of the youth vote was down from 66 percent in 2008, but

Youth turnout was roughly 50 percent nationwide, but climbed to 58 percent in battleground states. Moreover, Gallup’s final estimate showed that young people made up 13 percent of likely voters; they comprised 19 percent of the electorate. These discrepancies are a testament to his campaign’s freakishly persistent, efficient and effective field campaign.

The Obama campaign refined and escalated its ground-level efforts from 2008 with the knowledge that their biggest return-on-investment came from registering voters, and then having regular supporters talk to them. Its unprecedented level of targeting and ground-level investment did more to increase youth turnout and support than any ad, debate or policy position ever could. Coupled with an aggressive social media campaign that was proven to increase turnout, this pushed Obama’s youth vote share in the major swing states beyond his national share and propelled him to an Electoral College win.

If you’re looking to court young voters in 2014 or 2016, your big takeaway from 2012 should be that nothing beats old-school targeted voter contact. The work done on the ground isn’t sexy and it often goes unnoticed; it’s a lot easier to cover a new ad than it is to keep track of how many college students are registering to vote. But had it not built a firewall of young people, many of whom were not considered likely voters by pollsters, the Obama campaign would not have been able to hold the states necessary to secure a second term for the President.