So... What did happen in the 70's...?

[Spider Jerusalem]

38. The US stopped being able to supply domestic oil demand with domestic supply after 1970.

See here (total oil imports per year in thousands of barrels): http://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=MCRIMUS1&f=A

Total oil imports went from 483 million barrels in 1970 to 1.1 billion in 1973 and 2.3 billion by the end of the decade. This leads to an imbalance of payments with large currency outflows to pay for energy imports--Nixon ended convertibility of the dollar to gold, why? In part because of this balance of payments issue brought on by oil imports. The US went from a manufacturing economy to a service economy, why? In part because the economics of importing oil for raw materials for petrochemicals and plastics and a hundred other things combined with inflation in wages made it uneconomic to manufacture in the US, and the oil price shocks of the '70's meant less discretionary spending on manufactured goods for a lot of people, less discretionary spending means more layoffs in manufacturing industries producing those goods which leads to offshoring of production to low-wage countries by manufacturers in order to be able to sell to a market with less purchasing power.