At the close of the 19th century, more than 2 million American children under age 16--some as young as 4 or 5--were employed on farms, in mills, canneries, factories, mines and offices, or selling newspapers and fruits and vegetables on the streets. The crusaders of the Progressive Era believed child labor was an evil that maimed the children, exploited the poor and suppressed adult wages. The child should be in school till age 16, they demanded,...