Education in America may be a hot political issue, but pre-schooling is considered a private matter, best left to the particular tastes - and pockets - of families.
Although there are five million American pre-schoolers in some kind of centre-based education, there is precious little publicly-funded provision. And the few free places go to children considered "at risk".
"Parents accept it's their private problem," said Dr Barbara Willer, public affairs director of the National Association for the Education of Young Children, a national organisation in Washington. "They don't perceive that this is something that government should or could be doing."
Many American parents do accept that educating their under-fives brings social and educational benefits, and the research shows they are right. Children who have been to pre-school are better prepared for first grade, in terms of cognitive - as well as social and emotional - development.
Why, then, are so few nursery places funded with taxpayers' money? Partly the reason is that it has always been thus. Judith Rosen, director of the Office for Children in Fairfax County, Virginia, says it is "crazy" to use taxpayers' money for financing college education but not pre-school.
She also believes that the recession which began to bite in the late 1980s is partly responsible. Areas which were moving towards universal provision for four-year-olds halted it.
Dr Willer thinks that attitudes developed over decades of American history explain the phenomenon. First, Americans are hostile to government. Many do not believe it is the government's job to take care of young children.
In many parts of America, children begin compulsory schooling a year later than in Britain. The majority of parents, particularly those unable to afford good quality private pre-schools or poor enough to qualify for public places, make do with what is available locally. If they work, they may use babysitters or relations initially, and move on later to private centres.
There is a big tradition of private, non-profit pre-school education in the United States. Fees vary from Pounds 650 or less a year for three half-days to Pounds 3,350 or more annually for full-time private nurseries. Many parents belong to co-operative nurseries, housed in church halls or synagogues. These can be very small, with just one teacher, and rely on parents donating their time to help out.
Such co-operatives began decades ago, but the picture has changed dramatically since then, with increasing numbers of women going to work. Children's centres have opened all over America, taking children from the crack of dawn until late afternoon when parents return from work.
The trend of women working sits uneasily with the American emphasis on the family. But women's liberation in the United States was always seen as a way to ensure equal opportunities for women at work without thinking about the messy business of nurturing children.