1890s: The United States' economy expands rapidly as the nation exploits its natural resources. Large corporations in the transportation, steel, oil, meat-packing, and financial industries establish monopolies; as a result, Congress passes the Sherman Anti-Trust Act intended to break up such monopolies.

Today: Dozens of states and the federal government go to trial with the Microsoft corporation. Charged with being a monopoly, the company defends itself on the grounds that standardization is better for consumers than variety.

1914: World War I breaks out when Archduke Franz Ferdinand of the Austro-Hungarian Empire is assassinated in Sarajevo. The system of interlocking alliances among Europe's great powers compels these nations to go to war on each other's behalf. The war drags on until 1918; millions are killed.

Today: After a terrorist attack destroys the World Trade Center in New York, President George W. Bush calls for a war against...