TransCanada President and CEO Russ Girling comments on the approval of the Keystone XL pipeline route through Nebraska during a January 2013 news conference in Calgary, Alberta. Todd Korol/Reuters/Landov hide caption

itoggle caption Todd Korol/Reuters/Landov

A 2012 photo shows sections of pipe on a neighboring property to Julia Trigg Crawford family farm in Sumner Texas, in the path of the Keystone pipeline. TransCanada said today that it is delivering oil through the Gulf Coast portion of its proposed Keystone XL pipeline, from a hub in Cushing, Okla., to Houston-area refineries. Tony Gutierrez/AP hide caption

itoggle caption Tony Gutierrez/AP

Daryl Hannah is handcuffed and arrested during the Keystone XL Pipeline Protest at Lafayette Park in Washington on Wednesday. Leigh Vogel/Getty Images hide caption

itoggle caption Leigh Vogel/Getty Images

President Obama announces support for building an oil pipeline from Oklahoma to Texas, Thursday in Cushing, Okla. Tom Pennington/Getty Images hide caption

itoggle caption Tom Pennington/Getty Images

Demonstrators march with a replica of a pipeline during a protest to demand a stop to the Keystone XL tar sands oil pipeline outside the White House last November. Evan Vucci/AP hide caption

itoggle caption Evan Vucci/AP