1950s: During the cold war, Americans are afraid of infiltration by Communists. In Congress, the House Un-American Activities Committee holds hearings to find out if foreign elements have penetrated our nation's security.

Today: After the 9/11 terrorist attacks, Americans are once again wary of the country being infiltrated by hostile outsiders. The Department of Homeland Security is a newly-formed agency assigned the task of preventing attacks within the United States.

1950s: A young woman like Cindy Hilliard, working in a law office, is most likely to be, as Cindy is, a secretary.

Today: A young woman working in a law office is just as likely to be a lawyer or a paralegal.

1950s: Police are able to search for Glenn Griffin's girlfriend by monitoring all calls going from Columbus, Ohio, to Indianapolis over a four-hour period.

Today: With wireless communication and messages routed through various...