Thousands of spectators lined the shores as those in the procession marched across the causeway.
Many of the original construction workers returned to the area to reminisce about what was called an engineering marvel when it was built.
Cape Breton-Canso MP Rodger Cuzner was on hand to announce that the causeway has been designated a nationally historic site.
The causeway is about 1,400 metres long and up to 66 metres deep.
Cuzner said its construction, at an estimated cost of $23 million, made the Strait of Canso ice-free and a significant deep-water port.
"When you think back 50 years ago, what it took to create that causeway, with boulders the size of compact cars, you can get an appreciation of why we're so proud of this achievement by Nova Scotians," said Bob MacEachern, chair of the Canso Causeway Anniversary Society.
"At the time, the only thing linking, from a transportation point of view, Cape Breton Island with mainland Nova Scotia was a two-ferry service – one for the train service and one for passenger and auto service."
There was much talk about some kind of a permanent link, perhaps a tunnel or a bridge. In the final decision, a causeway appeared to be the most viable of all those options, MacEachern said.
"There are some tremendous stories that are told by construction workers who were on the site for three years," he said.
One is from a man operating a bulldozer, pushing the rock that was dumped in the strait one evening. Little did he know that the harsh tidal waves that are known in the area were eroding the rock as it was going down into the strait.
Before he knew it, he heard a gush and his machinery began its descent into the water.
"He was very lucky to be able to jump away and swim back to shore, and he was rescued," MacEachern said. "The piece of machinery went down in the Strait of Canso, and that's something in the range of 220 feet down."
A number of dignitaries were planning to attend the anniversary events, including the son of the late premier Angus L. Macdonald, who gave the green light for construction of the causeway.
