CALGARY, Alberta (Reuters) - Canada's two major pipeline companies did not have a good summer.

Enbridge Inc, which handles the lion's share of Canadian exports to the United States, had a series of pipeline ruptures that cut into the flow of oil sands crude to thirsty markets south of the border.

TransCanada Corp, the country's biggest pipeline company, faced bitter opposition from critics of one of its key growth plans: the $7 billion Keystone XL oil pipeline from Alberta to the Gulf of Mexico.

The pipeline breaks and opposition from US legislators and environmental groups looked ready to derail plans for the two companies' biggest potential source of growth — expanded shipments of oil sands crude to the United States.

But despite the headlines, the shares of both firms have emerged relatively unscathed. And analysts say this is for good reason.

The long-term need for oil sands crude in the United States — the backbone of growth plans for both TransCanada and Enbridge — remains unchecked. That's good news for the pipeline operators carrying that crude south.

"Cooler heads will prevail," said Bob Hastings, an analyst with Canaccord Genuity. "The US needs the oil."

Since Enbridge's Line 6B ruptured and spilled 19,500 barrels of oil into a Michigan river system on July 26, the first but longest of its three pipeline outages over the past few months, the company's stock has held fast, rising just less than one percent to close on Friday at C$52.23.

TransCanada shares have also been solid, rising 4.5 percent since the start of August to C$38.30.