What is the keystone?

Anons, maybe it's nothing, and I know, it's not the hot topic at the moment, but I need to throw this in.

I just watched some funny DJT moments, as I stumbled over the Presidential Debate and Trump was saying the following to Bush:

"The Keystone pipeline that you want so badly …"

Here is the Link (6:48):

https:// www.youtube.com/watch?v=gP93ibc3MMs