What is the "International Date Line"?

The "International Date Line" is indeed an imaginary line that separates two consecutive calendar days. It primarily runs along the 180-degree meridian in the Pacific Ocean, serving as the point at which the date changes. When you cross the line from west to east, you subtract a day, while crossing from east to west adds a day. This concept is essential for global timekeeping and helps regulate time zones around the world. Understanding the function of the International Date Line is crucial for travelers and anyone monitoring international time, as it directly affects flight schedules and time zone calculations.

The other options do not accurately describe the International Date Line. While it has implications for air traffic and international travel, it is not a geographical boundary in the traditional sense. It also does not serve to mark time zones specifically within the United States, nor does it indicate physical national borders, as it is purely a timekeeping mechanism rather than a geographic or political boundary.