After years of federal review, there was little question last year that construction of the pipeline, which would transport heavy, oil-like bitumen from Alberta to the Gulf of Mexico coast, should proceed. Thousands of miles of pipeline already crisscross this country. An environmental analysis had concluded that the risks of adding this new stretch were low. An economic review had found that Canada would get its bitumen to the world market — if not via pipeline to the gulf, then very likely by ship to China. Supply would make it to demand, one way or another.