OTTAWA -- For three decades, Terry Fox's mother and father held on to boxes upon boxes of handwritten letters, poems, lovingly painted artwork and other tributes sent to their son by Canadians moved by his astonishing marathon.

Other memorabilia connected to the iconic runner were scattered across various institutions -- items such as his Marathon of Hope T-shirt, or the jug of water he filled in the Atlantic at the beginning of his run in 1980 but never managed to dump into the Pacific as planned.

The Fox family now is teaming up with the federal government for an exhibition of more than 150,000 items from the Terry Fox Collection at the renamed Museum of History in Gatineau, Que. The showcase will open in April 2015, coinciding with the 35th anniversary of his Marathon of Hope.

Darrell Fox, Terry's younger brother, said a central idea behind the exhibit is to give back to Canadians after decades of their own giving.

"OK, yes, these are items that belong and that were attached to Terry Fox but this is also a collection that is from Canadians from coast to coast," Fox said in an interview.

"It is theirs, and perhaps we waited too long, but it's time to give it back and to share it with all Canadians. The Marathon of Hope wasn't a one-person operation, as Terry said."

One of those items is a letter in pencil by a schoolgirl named Sarah in 1980.

"I know how you feel Terry Fox. Don't worry we are trying to help."

Fox lost a leg to cancer when he was 18 and three years later took up the marathon on a prosthetic limb. His distinctive, hobbling gait became a symbol of stubborn determination and courage.

He started his run in April 1980, dipping his leg in the ocean at St. John's, N.L. The effort ended 147 days and 5,373 kilometres later outside Thunder Bay, Ont., when his cancer returned and forced him to abandon his project.

He was showered with honours. He was the youngest person ever named a companion of the Order of Canada. He was given the Lou Marsh Award for 1980 as the country's top athlete.

He died in June 1981, aged 22.

The concept of the exhibit was born two years ago, when Darrell Fox met with Heritage Minister James Moore to talk about the collection.

Author Douglas Coupland had published a photobook about Terry in 2005, and warned the family that they needed to protect the items properly.

Moore, whose riding encompasses Fox's hometown of Port Coquitlam, B.C., set the wheels in motion for the collection to be held at a Library and Archives facility in nearby Burnaby.

"Terry Fox is like a local hero -- the biggest high school in my riding is Terry Fox Senior Secondary, the theatre in my riding is the Terry Fox theatre," said Moore, who was four when the Marathon of Hope took place.

Darrell said the family has grown even more attached to the items as they collected and moved them to the facility.

"Any items that were part of Terry's story are significant for me, and having spent three months as a member of the Marathon of Hope, hanging out in a stinky Ford van, witnessing a miracle in the making every day of my life, it's just not something that escapes you or that you ever forget," said Darrell.

The exhibition will be held at the Museum of History, currently called the Museum of Civilization, across the Ottawa River from Parliament Hill. Some of the proceeds will go to the Terry Fox Foundation for cancer research.

A travelling version of the exhibition will also be developed, and some key documents in the Terry Fox Collection will be digitized. The Fox family says they would like to set up a separate museum someday.