(Just asking the following as an engineer who's always interested in building the most efficient system - I hate environinnies!.)
Why isn't the oil being refined closer to the source, rather than sending it across the continent, where then the refinery output will be sent AGAIN around the continent?
The problem with that is you still have to transport the refined products (more than just gasoline), which would mean...more pipelines! And more trucks, more rail, etc. That infrastructure is already in place at the existing refineries.
Certain refineries are set up to process specific types of crude oil. In Texas, we have refineries that are set up to process high sulfur (heavy) crude, like the Valero refinery in Corpus Christi.
Significant amounts of crude oil from Eagle Ford shale are now being produced that are close to Texas refineries, but there is talk that this oil may be exported, because the refineries don’t have the capacity to handle all of it, and it is a light/sweet crude that doesn’t require sophisticated refinery operations.