Enlarge / Pumping station for an oil pipeline in rural Nebraska. (credit: shannonpatrick17)

The Keystone XL pipeline was intended to connect oil (technically diluted bitumen) from the oil sands of Alberta, Canada to refineries and ports on the Gulf of Mexico. The pipeline was strongly opposed by advocates for action on climate change because the processing required to extract useful oil from the thick bitumen makes it an even bigger source of CO₂ emissions than usual.

In November 2015, the Obama administration rejected the pipeline after a long period of uncertainty, citing the contribution to climate change and a lack of significant benefits in terms of jobs and US energy prices.