Every July 1st, Canadians across the country celebrate Canada's birthday, on what's known as Canada Day.

But it wasn't always called that — it was, in fact, first known as Dominion Day, after Canada was formally acknowledged as the "Dominion of Canada" at the time of Confederation on July 1, 1867.

It's a day that marks the real start of summer — school's out, the weather is finally warm, and it's a signal to get out of town if you can.

Automobiles head up the highway, northward bound on Dominion Day in 1960. 0:18

So how did it happen that the name of the special birthday holiday had Dominion in front of it, and that it was changed to the simpler and more obvious Canada Day?

As we hear in this CBC Television clip from 1959, Canada was the first among the Commonwealth members to assume the "Dominion" title.

Queen Elizabeth, seated in the garden of her Ottawa home-away-from-home, delivers a congratulatory speech to Canadians on Dominion Day.

Queen Elizabeth, speaking from Government House in Ottawa, congratulates Canadians on Dominion Day. 0:57

In 1967, Canadians celebrated the start of the year marking 100 years since Confederation with the lighting of the Centennial Flame.

And they invited the world to Expo 67, the centrepiece of the year's celebrations.

Sky Ride and crowd at La Ronde during Expo 67. (Library and Archives Canada)

Canadians across the country marked Centennial year with countless special events and activities, and partied extra-hard on Dominion Day.

As we can see in this news report on the day in Toronto, there were parades, pony rides, a beard contest, and go-go music. Even the mayor brought his camera along.

Toronto joins Canada's 1967 celebrations with parades, pony rides, a beard contest and go-go music. 1:48

In 1970, then-prime minister Pierre Trudeau made the day a double celebration.

That year, Manitoba marked 100 years since joining Confederation. The prime minister and 19 members of his cabinet travelled by steam train to Lower Fort Garry, outside Winnipeg, exiting the train sporting engineer's caps and escorted to the festivities by a piper.

Prime Minister Pierre Trudeau arrives at Lower Fort Garry, July 1, 1970 (CBC Archives)

A heckler's shout threatened to take the joy away from the occasion, but the prime minister was able to bring the laughter from the audience.

With a quick responsive quip he was able to get back to his intended speech — including in it a little history lesson — with "Relax, buster ... this is a fun day."

A special steam locomotive brought Prime Minister Trudeau and 19 cabinet members to Fort Garry for Dominion Day and Manitoba centennial celebrations in 1970. 1:26

The day eventually came to be known in as Canada Day, with the squeaking through of a change to the National Holidays Act on July 9, 1982.

Trudeau was not even present in the House, but he announced the change in Kingston, Ont., that night.