In an election that generated a lot of firsts — first states to legalize marijuana for recreation and profit, first openly gay U.S. senator, the first Mormon presidential candidate battling the first black president — one fact sticks out, and not necessarily in a good way: This was by far the most expensive election in U.S. history. Neither President Obama nor GOP challenger Mitt Romney accepted public financing, leaving them free to raise massive amounts of money, and after the Supreme Court's 2010 Citizens United ruling, super PAC and 501(c)(4) "dark money" groups poured hundreds of millions into the election. And for all that cash, Obama was re-elected, Republicans kept control of the House, and Democrats retained the Senate. Here's a look at the super-expensive 2012 election, by the numbers:

$4.2 billion
Total amount raised during the 2012 election, for the presidential, House, and Senate races, through Nov. 4

$6 billion
Estimated amount the 2012 elections will cost when all the numbers are tallied

$3.8 billion
Total amount raised for the 2008 election, the previous record

Total amount spent on the campaign to re-elect Obama, through Oct. 17

Total amount spent on the campaign to elect Romney, through Oct. 17

Obama campaign field offices

Romney campaign field offices

1.1 million
TV political ads run since April, mostly in nine battleground states

$750 million
Cost to run those ads

Ads Obama ran in Ohio

Ads Romney ran in Ohio

Total political ads run in Ohio, including those of outside groups

Visits Romney made to Ohio in 2012

Visits Obama made to Ohio in 2012

Percent of the vote Obama won in Ohio, versus 48.2 percent for Romney

Wealthy donors who each donated at least $500,000, for a total of at least $290 million

$53.69 million
Amount (and counting) donated by Las Vegas casino magnate Sheldon Adelson and his wife to defeat Obama and other Democrats

4.2 million
Individual donors to the Obama campaign

States flipped in presidential vote — Obama won Indiana and North Carolina in 2008 and lost them in 2012

Net change in Senate seats, with results pending in Montana and North Dakota

Make-up of House before the election, in favor of Republicans, with five seats vacant

Make-up of House after the election, in favor of Republics, according to NBC News projections

Sources: ABC News, CNNMoney, The Huffington Post, NBC News, London Evening Standard, Politico