Much of the crude oil that would flow down the proposed Keystone XL oil pipeline would likely be exported as refined products by U.S. companies—a prospect that is stirring further debate over whether the project serves the nation's best interest.

Backers of the pipeline, which would carry heavy crude from Alberta, Canada, through the Plains states to Gulf Coast refineries, say the exports would be good for the U.S. economy by creating refinery jobs and helping to reduce the trade deficit.

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