1860s:The United States engages in the Civil War, a ground battle that divides the country and claims the lives of more than six hundred thousand Americans.

Today:Americans unite in their support of the war on international terrorism, instigated by a terrorist act on September 11, 2001, that claimed the lives of several thousand Americans. This new kind of war relies heavily on behind-the-scenes intelligence efforts, and the use of military ground forces and air strikes.

1860s:America experiences an increase in leisure travel, due in large part to the expanding railroad network which triggers a decline in domestic travel by slower, steam-powered river boats.

Today:Many Americans travel to all parts of the world for both work and pleasure. The fastest form of commercial air travel, the supersonic Concorde, can travel at more than two thousand miles per hour.

1860s:James Redpath establishes the...