The 37th parallel north is a circle of latitude that is 37 degrees north of the Earth's equatorial plane. It runs across several countries, including the United States, Spain, and Japan. This parallel is significant for various geographical and climatic studies, as it often marks the boundary between different climate zones. In the United States, the 37th parallel north passes through states like California, Nevada, Utah, Colorado, Kansas, Missouri, Illinois, Indiana, and Ohio. It is sometimes referred to as the "parallel of the UFOs" due to the number of reported sightings along this line.