The Obama campaign got a lot of things right in the 2012 election. One thing they didn't get right: that it wouldn't be a billion-dollar campaign.

The Obama and Romney campaigns and allied committees both cracked $1 billion in reports filed late Thursday with the Federal Election Commission, making 2012 the most expensive presidential race on record.

In the end, President Obama had slightly more than $1.1 billion spent on him by his campaign, the Democratic National Committee and the top super PAC devoted to his reelection, Priorities USA Action.

Mitt Romney, meanwhile, had right between $1 billion and $1.1 billion spent on him by his campaign, the Republican National Committee and his super PAC, Restore Our Future.

While the financial battle was very even overall, each candidate had his moments when he was more flush with cash than others, and the sources of that money were very different.

Romney obviously spent lots of money on the primary campaign and ran out of primary funds before September, being forced to take out a $20 million loan and struggling to compete with Obama's summer ad spending. He also got a lot more help from his super PAC and the RNC than Obama did from his super PAC and the DNC.

Obama was well-funded throughout but saw his fundraising drop off in the summer months and was outspent later in the game. His campaign itself had much more money than Romney's because it was able to take more small dollar donations. (Romney relied on big donors, who had to give most of their money to the RNC, which can take larger donations, and super PACs, which can take unlimited donations.)

Obama campaign manager Jim Messina said early in the campaign that the idea Obama would raise $1 billion for his effort was "bullsh**" -- a bit of expectation-setting, no doubt.

But he was wrong.