Why did this Administration approve the Alberta Clipper Pipeline way back in 2009 and will not approve the Keystone XL Pipeline now?

Doesn't such construction create thousands of infrastructure jobs that pay excellent money that would help our unemployed and the economy?

Hasn't pipeline construction been determined to be the safest way to transport product?

Doesn't transport by pipeline reduce transport by rail and tanker; the latter of which is alleged to be creating pollution and having an adverse impact on the environment, global warming, and climate change?

What is the difference between the Alberta and the Keystone - Tom Steyer?