This graph represents "Serious Incidents" of pipeline incidents over the past 20 years.
This graph represents pipeline "Significant Issues" over the last 20 years.
This map shows some detail regarding this current situation.
But another map of the reservation after the 1851 Treaty of Ft. Laramie between the U.S. government and nine Indian tribes shows the pipeline cuts clearly through the middle of this boundary.
And here is why many protestors feel the land does in fact still belong to the Sioux.
The lines of the reservation started changing without Sioux approval in the mid-1800s after gold was found in the Black Hills, according to Routel.
“The government, in particular Congress, passed a number of statutes unilaterally that altered the boundaries of the reservation and confiscated that land,” said Routel. “The U.S. Supreme Court later issued a decision saying that the government acted unlawfully when it did that and awarded the tribes a large sum of money. At the time it was more than $100 million to compensate for the taking of that land, but the tribes have refused to accept payment and instead want the land returned.”