The discovery of millions of barrels of oil on the North Slope of Alaska in 1968 triggered a national debate over the benefits of building the 800-mile long Trans-Alaska pipeline. On January 13, 1971, the U.S. Interior Department acknowledged the irreversible damage the pipeline would do to the environment but noted that this oil was “essential to the strength, growth and security of the United States” and that environmental regulations and oversight would “reduce foreseeable environmental costs to acceptable levels.” Final approval of the pipeline took nearly three more years with President Nixon signing the Trans-Alaskan Pipeline Bill into law on November 16, 1973.