In the end, it wasn't that close.
The election wasn't actually that close once one looks at cross-sections of the results:
* 270 electoral votes can be reached by winning the eleven biggest states. (The tipping point in the 11-state scenario is New Jersey.) Obama won eight of them (California, Florida, New York, Illinois, Pennsylvania, Ohio, Michigan, New Jersey, and Virginia). Romney won only Texas, Georgia, and North Carolina. Texas demographic trends favor Democrats sooner rather than later if the state party becomes better organized and fields good candidates. North Carolina is already a tossup. The day could come when the Democratic candidate begins the campaign with an unassailable advantage.
* Obama won 15 states (and DC) with 186 EVs by margins ranging from 11.8% to 84.3%. He won eight states with 86 EVs by 4.7% to 9.9%. That's 272 EVs, meaning that Florida, Ohio, and Virginia (0.9-3.0) were icing on the cake.
* Looking at wins by state in descending order of EV, Obama needed only 15 states for reelection. The tipping point in this scenario is Colorado.
* Obama won 56.4% of the vote in states casting >5M votes and 55.8% in states casting 3M-5M votes. (Romney won by similar a similar margin in <3M states). In short, Obama ran up big margins in the places where people live.
* Obama won five of the six states with 20 or more EVs. He entered the campaign with a lock on four of them (California, New York, Illinois, and Pennsylvania). Romney needed Florida more than Obama did, and still lost it.
* The West Coast is one heck of a blue bulwark: CA (55 EV, 21% victory margin), WA (12 EV, 14.1%), OR (7 EV, 11.8%). The Keystone States are nearly as imposing: NY (29 EV, 26.6%), PA (20 EV, 5.2%), NJ (14 EV, 17.1%). Together, the six states comprise 137 EVs.
The Republican party almost has to rely on serious missteps by the Democrats to overcome what has become a formidable structural disadvantage. If I'm a Republican, I'm thanking God/Allah/Buddha for gerrymandering and the favoritism shown by the Constitution for representation of small states in the Senate.
Nate Silver wrote that the country trended slightly to the right, but what we really have here are two countries. (I don't recall whether Nate adjusted for Citizen's United and voter suppression laws. It's likely too soon for that.) The one with the most votes is extending its commitment to the Democratic party.