WASHINGTON — Environmentalists have spent the past two years fighting the Keystone XL pipeline: They have built a human chain around the White House, clogged the State Department’s public comment system with more than a million emails and letters, and gotten themselves arrested at protests across the country. But as bad as they argue the 1,700-mile pipeline would be for the planet, Keystone XL has been a boon to the environmental movement. While it remains unclear whether President Obama will approve the project, both sides agree that the fight has changed American environmental politics.
