If any historian in the future asks me to suggest a name for the latter half of the 20th century, my choice will be the Era of Anxiety. Along with millions of other Americans, I've grown up hearing constant warnings about dangerous threats to our national security.
During my lifetime, many have claimed that mysterious forces are at work all around us, but that the truth about them is being suppressed by the authorities.
There's no mystery in pinpointing when this anxiety crept into our collective subconscious. The impact of two events some 60 years ago still resonate today.
In 1948, the Soviet Union began to seal off access to West Berlin from the Allied zones. By June 24, all land, rail, and river traffic had been stopped. President Truman quickly ordered an emergency operation to deliver supplies by plane. Planners thought the effort might continue for several weeks, but the Berlin Airlift didn't end until well into 1949.
It was blatant intimidation by Stalin, and all notions of postwar harmony between the two powers evaporated. The Soviets were probing for weak spots, and the West had to be on guard. As cold-war tension mounted, it would produce a range of controversial measures such as loyalty oaths, blacklisting, and covert spy operations.
Also, something happened on June 24 the year before that changed the way Americans feel about life on this planet and others. A man named Kenneth Arnold was piloting his small plane near Washington's Mt. Rainier and saw what appeared to be a formation of objects. He likened them to saucers skipping across water. Media began using the term "flying saucers."
The concept of aliens and spaceships was standard fare in comic books and science-fiction magazines, and strange objects in the sky had been reported for centuries. But Mr. Arnold's close encounter broke down all barriers and embedded the idea in mainstream culture.
Within days, similar sightings took place. In July 1947, a newspaper headline in Roswell, N.M., proclaimed that wreckage from a crashed saucer had been found. The story was later revised to say the debris was from a weather balloon, which sparked a debate that may never end. The appearance of UFOs nurtured a suspicion that government agencies conspire to keep us from learning the facts about a wide range of subjects.
The long-term effects of this anxiety are obvious. Statements by political leaders are seldom taken at face value anymore. The claim that important events happen at random is often dismissed as naive.
Sinister plots seem to lurk everywhere. Is it any surprise there are so many TV ads today for mattresses that help you sleep more peacefully? To me, the events in June of 1947 and 1948 were like two cultural volcanoes. A lot of the dust is still swirling around, and the sky will never be quite as blue again.
• Jeffrey Shaffer writes about media, American culture, and personal history.