The Gulf of Mexico oil spill was bad enough for BP to change its chief executive. It was not bad enough for the US to change its energy policy. Last month Barack Obama, US president, used the spill to call for a new push on clean energy. But weak follow-through, a divided Democratic caucus and a unified Republican opposition saw meaningful US energy legislation shelved last week. Now, the reality of a high oil price may be about to change America's petroleum habits, even if policymakers cannot.

It seems as if we have been here before. Mr Obama's post-BP address is strikingly similar to a speech given by President Jimmy Carter in the late 1970s, attempting in vain to use the last oil crisis to change US energy policy. Mr Obama acknowledged the parallels, but promised a different outcome. But while Washington's resolve faltered again, the industry's economics are not following the old script.

From the birth of the automobile until the 1970s, oil cost between $15 and $20 per barrel in current prices. Then, in 1979, the Iranian revolution saw prices shoot up to $80 per barrel. Cheap oil proved resilient, however, as countries outside the Organisation of Petroleum Exporting Countries responded with extra production, adding more than the total output of Saudi Arabia to global supply. The recession that followed the oil shocks also cut global demand by a tenth. Prices soon fell to their old levels, where they stayed for two decades.