The Iowa caucuses and New Hampshire primary owe their first-in-the-nation status partly to circumstance. Decades ago, Iowa's caucus was the initial step in a long, complex process that the state used to award delegates, which meant that the voting had to happen early in the year. New Hampshire was mostly trying to save money — by scheduling its primary on the same day as many annual town meetings, which were held before the spring mud season.

But circumstance has not kept Iowa and New Hampshire at the front of the line. An aggressive protection of their own self-interest has. As primaries and caucuses became a bigger part of US politics in the 1970s, officials in Iowa and New Hampshire have fought hard to stay first.

Democratic presidential candidate Pete Buttigieg has a narrow lead in the delegate count in Iowa. Credit:AP

"We weren't stupid," Cliff Larsen, a former chairman of the Iowa Democratic Party, once said. New Hampshire passed a law saying its primary always must be the first, and Iowa has been similarly protective. "Iowa caucuses are first-in-the-nation mainly because the state insists on remaining first," Kathie Obradovich, a prominent Iowa journalist, has said.

It's all worked out very nicely for the two states. A typical voter in Iowa or New Hampshire has up to 20 times more influence than somebody in later-voting states, one study found. Sometimes, the two states have turned a parochial issue (ethanol) into a national priority. Local hotels, restaurants, pollsters and television and radio stations have received millions of dollars in extra business.