A protest against the Keystone XL pipeline project on Sunday drew thousands of people to the White House in Washington, DC.
The Keystone pipeline, proposed by developer TransCanada Corp., would carry oil from the tar sands in Alberta, Canada to refineries in Texas.
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Protesters encircled the White House in an attempt to put pressure on President Barack Obama, as his government decides whether to approve the $7 billion oil pipeline project, the Associated Press reported.
If plans are approved, then the pipeline is expected to open by as early as 2013.
Among the protesters at the White House on Sunday were actor Mark Ruffalo and Presidential Medal of Freedom winner John Adams, the AP said.
Those in favor of the pipeline say it will reduce American reliance on oil from the Middle East, while opponents fear the environmental impact.
Canada's Postmedia News described the protests on Sunday as the largest to date against the pipeline, and cited organizers as saying that 10,000 people joined in the demonstrations.
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The actress Daryl Hannah was arrested in August during a protest against the Keystone pipeline involving around 100 people in front of the White House.
“We want to be free from our dependence on foreign oil and fossil fuels," Hannah told ABC just before her arrest.
"If Obama approves of this Keystone XL pipeline… it would be a disaster. These pipelines, it’s not ‘if’ it’s going to spill, it’s ‘when’ it’s going to spill," she said.