OTTAWA — For nearly 15 years, Stephen Harper has been the boss.

But when the House of Commons next resumes, Harper will be just an everyday opposition MP and someone else is going to be in charge.

The last prime minister who stayed on in the House for an extended period after losing a majority government was a prime minister Harper has often spoke glowingly about: John George Diefenbaker.

Dief the Chief was PM from 1957 to 1963 but then stayed on as the MP for the good people of Prince Albert, Sask., until he died in office in 1979.

Who knows how long Harper will continue to represent the good people of Calgary Heritage -- a year? Two? -- but however long he stays, his legacy as prime minister is undeniably a remarkable one.

"The party's recollection of him is already quite a warm one and will get warmer as time proceeds," said political strategist Rick Anderson, who has crossed swords with Harper as often as he has helped him, most recently in this last campaign.

BUILDING THE MOVEMENT

Harper started out as a policy wonk who didn't much like and wasn't much good at the glad-handing, back-slapping, back-scratching approach to politics. Nonetheless, he found a way to prevent the Canadian Alliance from self-destructing, mostly by ruthlessly hijacking its leadership from Stockwell Day, and then negotiating a merger -- with similar calculating ruthlessness -- with Peter MacKay, then the leader of the Progressive Conservative Party.

He then handily won the first and, to date, only Conservative Party of Canada leadership race. That one was against Tony Clement and Belinda Stronach. Remember that?

From there, Harper led the building of the machine that would be battle-ready to take on what was then the Liberal juggernaut of Paul Martin. He came close to beating the juggernaut in 2004 before besting it in 2006.

Now, he passes to his successor a party that is in much better shape than the Liberal Party was after Martin, the Progressive Conservatives after Mulroney, or even the Liberals after Pierre Trudeau.

"From a policy perspective, Mulroney left a bigger legacy," said Duane Bratt, professor and chair of the policy studies department at Mount Royal University in Calgary. "But from a political perspective, Harper's legacy is much better."

Still, there are some significant policy accomplishments for which Harper should get credit.

THE PEACEABLE KINGDOM

First and foremost, Harper's chief legacy was to put a Western flavour on our national politics and do that without fanning the flames of Quebec nationalism.

"The political and economic centre of gravity has shifted in this country under Harper," said Bratt.

At one point, Calgary was the home base of the prime minister, his de facto deputy (Jim Prentice), and the party's most capable political lieutenant (Jason Kenney). The summertime pilgrimage to the Calgary Stampede is now required of all political leaders, the Green Party's Elizabeth May included. It's a symbol -- but an important one.

So if Harper's legacy was to put the West at the heart of the political and economic centres of power in ways it had never been, will it remain so under Justin Trudeau?

The answer, so far, appears to be a qualified yes -- another Harper legacy.

Trudeau's campaign went out of its way to build bridges in Alberta, with a frank recognition that his last name was a handicap to Liberal fortunes there. He has a handful of seats to show for it. It's a start.

And from a purely strategic political point of view, the last two decades have taught the Liberals a very hard lesson about the perils to their party of Western alienation.

Meanwhile in Quebec, separatist sentiment dropped to an all-time low under Harper, despite the relative unpopularity of the Conservatives there. Contrast that with one dumpster fire after another on the national unity front through the Pierre Trudeau, Mulroney and Chretien years.

A largely peaceable kingdom after a decade of Harper. Who'd have predicted that a decade ago?

"Philosophically, he had a deep respect for provincial prerogatives," Anderson said.

HARPER'S POLICY LEGACY: TRADE AND AN APOLOGY

Harper's signature economic legacy will be, like Mulroney's, trade deals. When Harper took over in 2006, Canada had free trade deals in place with just five countries. As he leaves, trade deals are in place or pending with 51 countries, including the massive Canada-European Union trade agreement and just-concluded Trans Pacific Partnership.

Domestically, his biggest file was steering Canada through the worst global recession since the 1930s. He did as good a job, if not better, as any other G20 leader. And while many in Canada focus on monster deficits he ran to get us through that recession, it was equally important that he led an international crusade to prevent new tariff walls being thrown up in response to the economic crisis, something that would have killed a trading nation like Canada.

Historians will also note that it was Harper who made the official apology to aboriginal residential schools survivors.

His critics say he then failed to follow that up with concrete action to improve the lives of First Nations but that is something for competing politicians to haggle over. Historians will agree that it is an undeniable fact that without that apology, the relationship between Canada and the First Nations was not going to move forward.

It may also be worth noting that hero Dief was the prime minister who gave aboriginal Canadians the right to vote.

On foreign policy, Harper took us out of Afghanistan. And though there were Canadian combat missions in Libya and, currently, in Syria and Iraq, he was the first prime minister to allow Parliament to debate and vote on deploying our forces in an overseas combat mission. Our constitution did not require such a debate and vote but that's a new tradition that future prime ministers will now find it difficult to ignore.

Harper's multi-billion-dollar global and maternal health initiative gets little notice at home but has been widely praised globally by foreign governments and NGOs alike. That initiative alone has saved tens, perhaps hundreds of thousands of lives of women and children in developing countries.

LEAVING REFORM BEHIND

But then there were things that didn't get done, things that were important for many of the old Reformers who helped Harper to the top.

The single biggest demonstration every year on Parliament Hill is the pro-life rally held every spring. And though Jason Kenney showed up at one while he was an opposition MP, no senior Conservative ever dared speak to the thousands who rally. Nine years of a Conservative government, including a four-year-majority, and abortion access rights in Canada remain in the legal limbo they always have. Harper forbade his MPs from even talking about it in Parliament.

In 2006, Harper campaigned to reverse same-sex marriage laws that Paul Martin had passed. Harper made a half-hearted unsuccessful attempt then gave up. Same sex marriage now seems as uncontroversial as cream in your coffee.

The early Reformers wanted more direct democracy initiatives such as recall power of MPs. They wanted a national referendum on capital punishment. They wanted a triple-E Senate. None of that happened on Harper's long watch.

Maybe that's for the next guy or gal in charge.