President Trump signed an executive action on January 24 to advance construction of the pipeline. On February 7, under that executive order, the Army Corps of Engineers stated that they would allow construction to resume as soon as February 8.
The DAPL is a more than 1,000 mile-long oil pipeline that runs through four states: North Dakota, South Dakota, Iowa and Illinois. Native Americans and environmentalists spent several months in 2016 protesting construction in North Dakota, as they argued it could contaminate the water supply of the Standing Rock Sioux reservation and destroy its sacred sites. Obama successfully blocked that part of the route because it required an easement under Lake Oahe in North Dakota.
Why it matters:
Trump's successful resurrection of the pipeline signals his commitment to dismantling many of Obama's signature policies. Following his executive order, the Standing Rock Sioux stated that they would "vigorously pursue legal action to ensure the environmental impact statement order issued late last year is followed so the pipeline process is legal, fair and accurate." However, the Army's announcement on February 7 leaves the tribe with little time to find a legal option to prevent construction.