Lindsey Green tells the story of D.B. Cooper in her Medium post:

The man who hijacked Northwest Orient Airlines Flight 305 on November 24, 1971 was in his mid-forties. He bought a one-way ticket at the Portland International Airport counter under the alias Dan Cooper and became widely known as D.B. Cooper due to media miscommunication. When he boarded the plane, he took a seat in the rear. He lit a cigarette and ordered a bourbon and soda. He carried with him an attaché case and a note written in neat, all capital letters, which he passed to the flight attendant. Thinking the slip of paper was nothing more than a phone number, the attendant dropped the note in her purse, prompting the well-dressed man to lean over to her and say politely, “Miss, you’d better look at that note. I have a bomb.”

She did as instructed and looked at the note, which read: “I have a bomb in my briefcase. I will use it if necessary. I want you to sit next to me. You are being hijacked.”

The line that always stuck out to me was “I want you to sit next to me.” There’s something oddly human about it, despite the cruelty of the task being carried out. A calling card of Don Draper’s character when he’s at his most desperate.

The hijacker’s demand? According to Wikipedia,“$200,000 in ‘negotiable American currency’; four parachutes (two primary and two reserve); and a fuel truck standing by in Seattle to refuel the aircraft upon arrival.”

It is entirely possible Mad Men is setting up for an ending where Don Draper is D.B. Cooper.

The whole series is about identity, asking: "What compels a person to do something like that?"

Season 7 -- the last season -- will be about the end of the 1960s, so the timelines match up.

Fascinating theory.

This kills the the fantasy of DB Cooper still being alive today. Don Draper's lifestyle has me thinking he'll drop dead by 1970 anyway

There is a lot of death on the show, so it would not be a big surprise if the series ends with him dying.

I'm beginning to believe the DB Cooper theory.  Open-ended would be the only way to leave it, with us imagining what Don Draper is doing every day for the rest of our lives.

Remember Don's Royal Hawaiian pitch?  An empty beach chair and footprints leading into the ocean. That's how we're to remember him.

Yes! Open-ended would also follow the gold standard set by the Sopranos.

Airplanes, Airlines, and Flying are an ongoing theme in Mad Men's first six seasons.

Great quotes from Lindsey's article:

“Happiness is freedom from fear. It’s a billboard on the side of the road that screams with reassurance that whatever you’re doing, it’s OK. You are OK.”

“People tell you who they are, but we ignore it — because we want them to be who we want them to be.”

 “What makes someone do something like that?”

Mad Men has dihedral effect. 

Lindsey M. Green's theory hijacked my thoughts for most of the day. 

"Lindseymgreen.  I work with startups. I like sports and small furry animals. My cat's name is Chauncey."

Someone should recruit her.

I think I've re-read Lindsey's post ten times. The theory has built a nest in my mind.

If the writers hadn't thought of this ending yet, they certainly can't NOT think of it now.

"Who was D.B. Cooper and why did he do what he did?" is a thought provoking question.

"Who are we and why do we do what we do?" is also thought provoking.

The look Don and Sally exchanged at the end of season six ("This is where *I* grew up .... " as he motions to a tenement building) made me wonder why a father would bestow that information on his daughter ...... unless he knew he'd be referencing it later in a life/context that included her.  It felt like he was opening a door, not closing one.  

Still, there's the why.

Perhaps season 7 will go into the why.

I need to find Sterling's "doors and bridges" monologue from season 6 episode 1.

If I recall correctly, he specifically says our experiences do not change our path.

Found it:

"What are the events in life? It's like, you see a door. The first time you come to it, you say, 'Oh, what’s on the other side of the door?' Then you open a few doors and then you say, 'I think I want to go over a bridge this time. I’m tired of doors.' Finally you go through one of these things, and you come out the other side, and you realize that’s all there are: doors! And windows and bridges and gates. And they all open the same way. And they all close behind you. Look, life is supposed to be a path, and you go along, and these things happen to you, and they’re supposed to change your direction, but it turns out that’s not true. Turns out the experiences are nothing. They’re just some pennies you pick up off the floor, stick in your pocket, and you’re just going in a straight line to you-know-where." (S6, E1)

Many more Roger Sterling quotes...

What happens to D.B. Cooper:

The highjacker’s chosen flight attendant went to the cockpit to inform the pilot. When she returned to her post, the hijacker was wearing dark sunglasses. Throughout the ordeal, Cooper kept up conversation with the flight attendants, who later described him as “nice, thoughtful, polite, calm and well spoken.” They noted that he was in no way nervous, and he even pointed out landmarks on the ground to them. When he ordered a second bourbon and soda, he paid his tab, insisting the flight attendant keep the change.

Once his demands had been met, Cooper allowed all the passengers to de-plane in Seattle. He took off again with just the captain and the crew, instructing them all to stay in the cockpit and leave the door closed. He demanded particular speeds and altitudes. When the plane finally landed again at Seattle Tacoma Airport, police and FBI came on board to discover that Cooper was gone, and the back aft airstair of the plane deployed. The crime was never explained. It remains unsolved. And Cooper remains at large and unidentified.

I read this recently. Very compelling. I hope it's accurate. I remember a bit about D.B. Cooper from Prison Break, this would be SO much better. 

Christy, I agree. SO much better!

I especially liked the analysis that season 6 is a mirror of the first season:

What’s more salient to this theory is that the current season of Mad Menis a mirror image of the first. Creator Matthew Weiner is interweaving the skeletons of scenes we’ve seen and scenarios we’ve lived before, and even recycling lines from the inaugural season. His characters have been placed back at their starting points, before they had changed form or identity through the years:

• Don is cheating on his young wife, who is growing restless with his behavior.
• Peggy is in love with a married man and fighting for relevance at work.
• Joan is the most powerful person in the office but has no real power.
• Pete Campbell angrily uncovers someone’s true identity (his shotgun is back too).
• Betty is thin, blonde, and beautiful again.
• Duck Phillips is suddenly around.
• Perhaps most tellingly, the agency is once again Sterling Cooper.

If Mad Men's first five seasons just managed to bring Don Draper back to where he started, season 7 could bring him back to a place he occupied before the series began: free, alone, and without identity.

Not quite a circle since it will end up further back than it started.