clinton has the right answer for the right reasons, but the political part of it needs to take two things into account:

1) long-term projections suggest that there's not going to be a lot of demand for tar sands oil in western-aligned states over the next decade or so. transporting by rail with the cost of oil this low may even run at a loss. the market is such that this is not going to be necessary for quite some time.

2) what that means is that it is even more clear than it's ever been that the primary customer for this oil is china. and, that's what this is really about.

the decision is being made by the state department. the state department doesn't make decisions based on environmental assessments, although it may pretend it does sometimes. the state department makes decisions about the american national interest, strategies regarding access to resources, geo-politics and national security. the state department would consider canada to be within it's sphere of influence and that the united states has de facto ownership of canadian resources as a result of it. when you get your head around the way they see us, it's entirely logical for them to conclude that selling our oil to china is a national security threat - it takes oil they believe belongs to them and siphons it away to their competitors.

that is the actual issue, here: they waited it out because it wasn't entirely clear that blocking transfer was the best way to hem the oil in for later. if the price of oil had increased dramatically, for example, it would remain profitable to ship it over the rockies, and it would be strategic for them to have ultimate control over transit lines. it's the state department. they put tremendous resources into controlling pipelines, the world over. they would rather it ship through the contiguous united states, where they can ultimately control it, than through canada straight to the tankers in bc.

but, with the cost this low, virtually any method over the rockies is uneconomical. it follows that opposing the line can be safely pursued as a way to maximize obfuscation in the export process

www.cbc.ca/news/business/hillary-clinton-keystone-xl-1.3239215

wattajoke
Interesting observation, especially considering that the only country the US has increased oil imports from over that last five years is Canada.

http://www.eia.gov/dnav/pet/pet_move_impcus_a2_nus_ep00_im0_mbblpd_a.htm

However, about 99% of our oil exports go to the US.

https://www.neb-one.gc.ca/nrg/sttstc/crdlndptrlmprdct/stt/stmtdcndncrdlxprttpdstn-eng.html 

Perhaps they have us over the (oil) barrel?

jessica murray
well, yeah, that's exactly the point - they don't need our oil right now; they're producing enough that they're exporting it themselves. so, if we're trying to boost production, and they're not buying, that means it has to ship somewhere else. and, it's pretty clear where that destination is, and why they don't want that to happen.