So where does John Key sit in the scheme of things?
Numerically Keith Holyoake beats him, and Jim Bolger and Helen Clark had three terms.
Which is the surprising thing about all of this - why not a fourth term? He has said he intended to chase a fourth and that hardly ever happens.
The record books were calling but the record books aren't that important.
Britain Prime Minister David Cameron had a plan. He won two terms - which are five years in Britain - and he got a majority in the second term out of a coalition so his legacy was polished nicely.
He stared down the Scottish vote, and was supposed to stare down the Brexit vote, hand over the reins and walk away a hero. Great plan.
The trouble with what John Key has done is that he's walked away from the history books and hampered his party in the process.
But in terms of his legacy he is the best Prime Minister of my lifetime.
Norman Kirk wasn't around long enough, Bill Rowling was an abject failure, Robert Muldoon was a tyrant, and David Lange started with a burst, showed amazing promise and brought a personality to the game we hadn't seen in a long time, if not ever, but he imploded.
Geoffrey Palmer was hopeless and Mike Moore a disaster, not through his own doing but his party being a mess.
Jim Bolger was around long enough to be good but not great and Jenny Shipley was okay but not round long enough.
Helen Clark would be second to Key. She served three terms and was good for the economy. She also got out and about and brought a new style to leadership.
She was everywhere. She worked out that being everywhere was good for the image. But as poltically sucessful as she was, she never really got past the fact she was aloof. She wasn't really one of us.
Key changed that. He is a rock star, he was the selfie Prime Minister.
Key took Clark's lesson in being places and turbo charged it - God nows how many air miles he's flown.
He's travelled more than anyone, he's been omnipresent, he's a popularity magnet, he swings votes and he's Teflon-coated.
He is his party's greatest asset, he kept the opposition parties at bay. In an MMP enviromemnt to end the year on 50 per cent polling is unheard of, and because of that the gap he leaves is enormous.
But perhaps the best thing is he loved it. He arrived looking to acheive stuff and he's done it.
He did what he set out to do. And now having ticked the boxes he leaves at the peak of his popularity and powers.
It doesn't get any more impressive than that.
He's not just our best Prime Minister of modern times but the best by some margin.