In the new industrial cities, children worked. Children had always worked on the farm, but now they're working for a stranger in a factory, that has very little interest in them. So wages are set by supply and demand, and less experienced workers may be less productive, but they're cheaper. And because kids were cheaper, they were often sought out to replace adults. So children as young as six and seven would be working 12 and 14 hours a day in a factory. So the debate about how to protect children, and what kind of a minimum wage, and when children should be working, continues to this day, in a conversation about something called the training wage. But on the other hand, we do, in this period of time, create child labor laws that require that children not work, first at 10, then to 12, then to 14, and then to that current normal age that children are not legally able to work, except in some exceptions, is the age of 16. And children are expected, therefore, to go to school and develop. So we created policies related to the idea of childhood. I spoke earlier about mother's pensions. We created the child labor laws, and took children out of work. We created mandatory education, up to 16 eventually, and we created a family court, a juvenile court, so that children were treated, not as criminals, but as growing human beings that need to be developed. Now, this idea had it's failures, but it was certainly an effort to build a safer place for children. So initially, the idea of childhood was spare the rod, and spoil the child, and the child was, by the time they were three or four, was gathering eggs and working in the garden. Children were perceived as part of the workforce. But in 19th century, we began to think that maybe this developmental stage of children was something quite different. And in progressive era, we set a side children before the age of puberty. Marriage laws were set, so that women wouldn't be forced to marry before puberty. Boys were not expected to go into apprenticeships before puberty. We created education before puberty, and we created a safe time for childhood development. In the 20s and 30s, we expanded this to include adolescence, the teenage years, and high schools expanded. We began to take children, adolescent children, out of the workplace. We began to take them out of the adult courts, and the adult prisons. And so, this extended it, so at the time of the Second World War, the normal age of marriage was 18, not 14, which it had before been. And that we expected to have this developmental period, from birth until 16 or 18. After the Second World War, this expanded, especially for white people, and for those with any kind of privilege to the college years. And so, it became increasingly necessary that people go to college. And the age of marriage, for college educated people, became 21 or 22 or 23, after they graduated from college. And this extended period of development grew further. And then, in the present era, we're considering people in their 20s still in development. And we call it the 20 something, as people explore their careers, and build out their capacities. And for many people, the age of first marriage is now in the 30s. So this development of a specialized time of child development, is really a 20th century idea, that we're continue to develop in the 21st century, and is something that is going to be central to the development of social policy.