1940: England and France were at war with Germany, Italy and Japan: later that year France, Belgium, the Netherlands, Luxembourg, Denmark, Norway, and Romania fell to the Germans, but the United States did not join World War II until Pearl Harbor was bombed in December of 1941.

Today: Having been elevated to the status of world power as an outcome of World War II, the United States is almost certain to be involved in any major worldwide conflict.

1940: The first Social Security checks were mailed out to Americans. The first payout to American pensioners totaled $75,844.

Today: After decades of workers paying into the system, the amount paid out annually by the Social Security Administration is nearly $400 billion.

1940: Plutonium, the radioactive element that fueled the nuclear bombs used in 1945 to end World War II, was first discovered.

Today: Now that the Soviet Union has disbanded, there are...