The vast majority of this production is reaching refineries by rail not pipeline. According to the North Dakota Pipeline Authority about 60% of Bakken oil is moving by rail. Only rail networks reach into the interior of the west were the resource is located and the refineries are not. The Keystone XL project is really only important to Canada's Alberta tar sand devastation. Without radically increased transportation volume most of Alberta's bitumen is uneconomic to develop; Canada, not the US, needs the Keystone Project to be finally approved. Consequently, carloads of crude oil have skyrocketed. In 2008 just 9,500 carloads moved by rail. In 2013 carloads originating in the US will near 400,000.
Natural gas is designated the "go-to" fuel for electricity production until, perhaps, politics allows renewable energy to shoulder the load. Natural gas now accounts for 28% of US electricity generation. Coal still tops the list of fuels at 39%. Coal trains that present their own environmental problems are decreasing in number. In 2012 the US originated the lowest annual number of coal carloads since 1993.
So now you know why US says: take the train.