So far, those fighting the Dakota Access pipeline have shrugged off the heavy snow, icy winds and frigid temperatures that have swirled around their large encampment on the North Dakota grasslands. But if they defy next week's government deadline to abandon the camp, demonstrators know the real deep freeze lies ahead. Life-threatening wind chills and towering snow drifts could mean the greatest challenge is simple survival.
Above: A student walks into the school at the Oceti Sakowin camp where people have gathered to protest the Dakota Access pipeline near Cannon Ball, North Dakota. The school teaches on average 20 students a day in the traditional Lakota curriculum as well as math, reading and writing.