The $8-billion Trans-Alaska Pipeline System (TAPS), one of history's most difficult engineering feats, was the largest private construction project of its time.
Built in 1975-77, the 800-mile, 4-foot-diameter, zigzagging pipeline carries crude oil from 250 miles north of the Arctic Circle down to the terminal at Valdez, the nearest ice-free port.
About half of the pipeline is above ground as it crosses three mountain ranges, 34 major waterways, and some 800 small streams. Inside Pump Station No. 9, three pumps put through about 1.2 million barrels of North Slope oil a day. Traveling at 5.4 mph, the oil takes 6.2 days to traverse the pipeline.