Recent debate over the Keystone XL oil pipeline has turned a spotlight on Canada's controversial and oil-rich tar sands, which would be the source of crude oil flowing through the pipe to the Gulf of Mexico.
Tar sands oil has faced stiff criticism from environmental groups, which say that it's far dirtier than its Middle Eastern counterpart despite claims from the Canadian government and industry groups that they keep a close eye on environmental impact.
But long before the Keystone XL became a cause célèbre, tar sands oil was already ubiquitous in America: It goes to fuel our cars and corporations' trucking fleets, and it's used in the production of products from aluminum cans to asphalt.
Starting last year, San Francisco-based environmental advocacy group Forest Ethics launched a campaign to encourage American companies to boycott tar sands oil and, specifically, the refineries that process it.
Using data from the federal Energy Information Administration (which tracks imports of unprocessed crude oil), Forest Ethics compiled a list of nearly 50 US refineries that handle tar sands oil (MoJo made the above map based on that list). In these refineries, the heavy, molasses-like "bitumen" from the tar sands undergoes heating, blending, and other refining steps and comes out as useable fuel, ready to be pumped into a long-haul semi.