214
The she-demon at the crossroads promised Dean a year, but only 214 days had passed when the end came. He didn't die on a hunt, or in a barroom brawl, or facing down the FBI. Although "stubbornness" should have been listed as the cause of death, it was officially recorded as "misadventure".
Dean was returning to the salvage yard after a quick solo hunt. Day 213 had been spent doing research, Night 213 playing duck and cover in the woods with the local law, and he excavated a very big dig on Day 214 trying to find the remains of the spirit in question. By the time the salt-and-burn was done, he was exhausted. Instead of getting a room, which was becoming increasingly risky, he decided to keep going. He'd get some coffee, he'd be fine...
Sam was pouring through Bobby's library, hope in his heart, breathing rapidly at the thought that he was onto something that would break the deal, when Bobby uttered a heartfelt, "Christo!" and turned up the volume on the TV.
Because Dean was been one of the FBI's most wanted, there was network coverage of the wrecked Impala. Sam caught a glimpse of Hendrickson directing the media circus amid rescue crews giving the cameras sidelong looks as they swaggered past pushing a covered stretcher. He stared at the screen in stunned disbelief, waiting for his phone to ring, waiting for Dean to have a fit that the Impala was wrecked again, that he'd tangled with another shape-shifter. He'd been so close to breaking the deal! There was a loophole in one of Bobby's oldest books---it would've meant learning Greek, but Sam was primed to do it---and the irrational guilt that he couldn't save his brother followed him for the rest of his life.
It took days for the results of the genetic testing to come in, for Sam to finally believe it. The trouble was, there was no one to protest to. It wasn't fair! The hellhounds hadn't come, it hadn't been a reaper who'd plucked him from the living---an ordinary accident was an unworthy end for the greatness that had been Dean Winchester. Forever after, the sound of loud rock and roll coming from a car window made Sam's heart ache.
Sam didn't know that there were other loopholes, not written in earthly books, but Divine Law nonetheless. The hellhounds didn't get his brother, thus thwarting the crossroads demon. Sam, the reluctant recipient of Dean's sacrifice, was protected from the repercussions. He was an old man before he learned the truth. The light at the end of the tunnel was Dean's welcoming smile.