In 1913, Congress authorized dam construction in Yosemite’s Hetch Hetchy Valley, despite objections of conservationists.

After the civil war, the country faced dramatic change as a landscape of farms and villages yielded to factories and sprawling cities. An abundance of labor and plentiful raw materials brought prosperity to many, and the image of the United States as a beacon of freedom and opportunity encouraged immigration from all parts of the world. Many workers, including immigrants, racial minorities, and children, however, often toiled long hours in dangerous conditions for little pay. By the turn of the century, reformers in Congress were pressing for new ways to make government more responsive to the needs of poor farmers, laborers, and urban dwellers.