The 21st Parallel North is a circle of latitude that is 21 degrees north of the Earth's equatorial plane. It runs across several countries, including parts of Mexico, India, and Egypt. This parallel is significant in geography and climate studies, as it often marks the boundary between tropical and subtropical climates. In addition to its geographical importance, the 21st Parallel North also intersects various cultural and historical regions. For instance, it passes near the ancient city of Cairo and the Sahara Desert, highlighting the diverse environments and human activities found along this latitude.