Barack Obama’s emphatic win in Iowa 10 days ago was widely portrayed as a historic moment in America’s political story. The fact that a black American could win in the overwhelmingly white state of Iowa was seen as a tipping point. But that may prove to be a premature – as well as historically glib – judgment of what took place.

First, it has happened before. Jesse Jackson, who was a much more overtly African-American candidate in 1988 than Mr Obama is now, won 11 primary elections in his ultimately losing bid for the Democratic nomination, including the largely white state of Vermont.