It is true that a lot of people choose to have multiple children in U.S heartland. We have three, most of the people we know have more than 2,3,4 or even 5, 6 children. One of my friends living in Northern California ,Napa Valley, had 12 children. They live on a family farm though and have lots of land. The couple are in their late 40's and are already grandparents themselves. I feel so envy of them! Children are the best gifts from Providence! American people make their own decisions about family size based on personal interest. There are no government regulations or influences so any size of family is possible. But families with single children are extremely rare. I mean, if you can afford one, why not have more? The costs per child are going down after three and more. Three is a good size to me. The rivalry among siblings also goes down when there are more kids.