When Europeans first came to America, their social values actually required children to work. In 1641, when the Pilgrims were urged to grow hemp as a raw material for winter clothing, the Massachusetts Bay court ordered (scroll down 10%) "all hands" to be employed in "the working of hemp and flaxe and other needful things for clothing." "All hands" specifically included children.
The Colonies also adopted "poor laws" similar to those in Europe. Working-class children, as young as three, could become apprentices.
By the turn of the last century, American children regularly worked in mines, fields, mills, canneries and other such places. The census of 1900 reported that 2 million children were employed throughout the country, For comparison purposes, that is roughly half the number of slaves reported in the 1860 census.
This is a pictorial story of those working children.