1860s: The American Civil War is fought, and when it ends in 1865 there are 620,000 dead soldiers.

1910s: World War I is fought. Between April 1917 and November 1918, 116,708 American servicemen die.

Today: The United States fights wars against terrorism in Afghanistan and Iraq. The modern war involves more advanced tactics supported by advanced technology in the areas of weaponry and defense, and fewer American lives are lost as a result.

1860s: The great railroads are built across the United States.

1910s: The aviation era begins. In 1919 the first transatlantic flight takes place, from Newfoundland to Ireland. The flight takes sixteen hours and twenty-two minutes.

Today: The commercial airplane is the way most people prefer to travel from city to city within the United States. Unlike Europe, which has a thriving rail network, the use of the railroad system in the United States is in decline.

1860s...