Nebraska was the final state along the pipeline's route to approve the pipeline's path. After surveys of the route indicated that the pipeline would not affect environmentally fragile areas, the governor gave his approval for the project, joining with other states who had already approved the project.
With this approval, the only obstacle that would remain for construction and operation of the pipeline would be an order from President Obama. Obama had blocked the pipeline last year, citing uncertainty over the project’s route through environmentally sensitive land in Nebraska - but that hurdle has now been cleared.
The State Department is expected to decide within the next several months whether to permit the project to go forward, but the decision removes the last stated public hurdle - or excused - that would have been used. Multiple analyses by the State Department are indicating there would likely be no effect on atmospheric or ground-level emissions as a result of the pipeline, and the tax revenues to be gained by states along the pipeline would significantly help state budgets.
It is possible that another reason is pulled out of thin air - after all, it is now the second term and there are no more elections for this President to worry about facing the voters' wrath.
The Keystone XL Pipeline would bring oil generated from Canadian tar sands into the Americas and help reduce American dependency on unstable regimes for energy (such as Venezuela, the Middle East, and Nigeria). The pipeline could generate between 800,000 and a million barrels of oil per day for the United States.