The 28th Parallel is a circle of latitude that is 28 degrees north of the Earth's equatorial plane. It runs across several countries, including the United States, Mexico, and parts of North Africa and the Middle East. This parallel is often referenced in discussions about climate, geography, and military strategy. In the context of the United States, the 28th Parallel is significant as it roughly marks the boundary between the southern and northern regions. It has historical importance, particularly during the Cold War, when it was associated with military operations and geopolitical tensions in various regions, including Korea and Vietnam.