The Keystone XL pipeline from Canada to the Gulf of Mexico is not for getting oil into the United States, it's for exporting it out (tax free!) -- and for getting world prices for what is sold in the US.
Here's Maclean's Explaining Canada’s hurry to build pipelines in the U.S.:
[T]wo sources of growing oil production feed largely into the Midwestern market: Canadian production, both conventional and oilsands, and U.S. Bakken production in North Dakota and Montana.Estimates are that this keeps the price of gasoline in the Midwest lower by 10 to 20 cents.
. . .
Normally, it’s possible to take care of excess imports into one region by moving excess supply to another region, and that has been happening in this case too, but just not quickly enough.
. . .
Even with the added shipments out of the Midwest, a glut of oil remains, and the excess supply has pushed down prices. In the last year, the spread between what a barrel of oil is worth in the Midwest (called WTI–which is usually the oil price you see on the nightly news) and what it’s worth either on the Gulf Coast (LLS) or when shipped to Europe (called Brent–which is generally used as a benchmark for world prices) has widened to historic levels.
Here's Congressman Markey addressing the Keystone exec on it:
The money quote in the above (about 1:11 to 1:52):
The US may just become the middle-man for shipping products made from some of the dirtiest crude oil on earth to foreign markets around the world. In fact, nearly all of the refineries where the Keystone crude will be sent are located in Port Arthur, Texas, which is a designated Foreign Trade Zone. This means that if these refineries re-exported diesel or other refined product, they wouldn't even have to pay US taxes on those exports.A senate amendment to the Keystone pipeline bill last week would have required all produce from the pipeline to be sold in the US. That amendment (along with another one requiring that construction use Made-in-USA steel) was roundly defeated. Google cached The National Association of Manufacturers' Capital Briefing for March 15, 2012 crowing that:
The NAM also key-voted in opposition to an amendment offered by Sen. Ron Wyden (D-OR) that would have banned the export of any crude oil, or petroleum products derived by crude oil, transported by the Keystone XL pipeline. Manufacturers' strong opposition to needless government interference in business operations helped strike down the amendment by a vote of 33-65.The only real commentary I can find on this is from Eleanor Clift in The Daily Beast from Mar 3: Do Republicans Realize That Keystone Pipeline Won’t Bring Gas to U.S.?