1960s: In the midst of the Cold War between the United States and the Soviet Union, each side monitors Latin American countries and maintains active spy networks within them to make sure that they will not form an alliance with the other.

Today: Since the collapse of the Soviet Union in 1991, Communist parties in Latin America have little support, and so most are shifting toward capitalism.

1960s: Because of the low value of the peso, American tourists flock to Mexico for cheap vacations and inexpensive merchandise.

Today: Mexico is still a popular vacation site but not because of its price: several coastal areas have built resorts that have good reputations for sun and water sports.

1960s: The environmentalist movement is launched with the publication of Rachel Carson's book Silent Spring in 1962. The book warns of the dangers of pollution and makes readers worldwide aware...