Chairman Tim Schram of Gretna said members of the Nebraska Public Service Commission won't immediately comment on their decision because of possible appeals.
However, three commissioners issued separate written opinions: Rod Johnson, who concurred with the majority decision, and Mary Ridder and Crystal Rhoades, who dissented.
Johnson's district covers east-central Nebraska and includes much of the approved route for the Keystone XL.
"(TransCanada) has made quite a few promises to Nebraskans, both in their application and during the course of this proceeding," Johnson wrote in his concurring opinion. "There should be no doubt that this commission and the citizens of this state expect TransCanada to keep those promises, and we will be watching to make sure that they do so."
Ridder's district covers western and central Nebraska, and includes the northernmost part of the approved route for Keystone XL.
She dissented, saying TransCanada should have considered following the route of the original Keystone pipeline instead: "An existing utility corridor that is both feasible and beneficial does exist but was discarded as a route because the applicant chose a 52-mile shortcut through Nebraska's Sandhills."
Rhoades' district is based in urban Omaha and isn't part of any proposed Keystone XL route, but she has been the commission's most outspoken critic of TransCanada's plans.
"The applicant provided no evidence to support a finding that the route is in the public interest," she wrote. Specifically, she said the commission lacked sufficient information about the mainline alternative route, violated the due process rights of landowners who are part of that route but not the preferred route, and improperly limited the role of environmental groups and Native American tribes in the proceedings.