Last week, as much as 1,600 gallons of oil spilled into Lake Michigan from the BP refinery in Whiting, Indiana, 20 miles from Chicago. After a week-long cleanup, authorities say they have found no further trace of spilled oil in the area. However, the political ramifications of the spill are likely to remain long after this incident. The BP refinery processes oil from tar sands found in Canada. Tar sands contain a thick petroleum that’s gaining popularity as a new energy source. New technology is making it easier to mine tar sands, but some worry that could increase the likelihood of more spills like the one last week.