In November, 1944, the Japanese began launching unmanned bomb-carrying balloons, which should travel on the theorized jet stream winds across the Pacific Ocean to North America. Some ballons reached the US and Canada. They would have proved the existence of the jet stream - if the Japanese ever had learned that they've actually made it.

The jet stream may extend for thousands of miles around the world, but it is only a few hundred miles wide and less than a mile thick.

Some cool facts.

On average, the jet stream flows from east to west, but it often meanders into northern or southern moving loops.