The Trans-Alaskan Pipeline crosses Alaska’s North Slope, carrying oil from Prudhoe Bay south to Valdez, Alaska. North of the Yukon River, 420 miles of the 800-mile pipeline were built above ground because of the unstable soil conditions from thaw-sensitive permafrost.
The pipeline was purposely built in a zigzag configuration to allow the pipe to move more easily from side to side and lengthwise in cases of earthquakes or temperature-related fluctuations. The effectiveness of this design was proven in 2002 when the pipeline survived a 7.9 magnitude earthquake.
The pipeline was built after the 1973 oil crisis caused a sharp rise in oil prices in the U.S.
Opposition to construction of the pipeline came from Alaska Native groups concerned because the pipeline would cross native lands with no economic benefits to inhabitants. Conservationists were angry at what they saw as an incursion into America’s last wilderness.