What is southernmost boundary?

The southernmost boundary of the United States is the border between the United States and Mexico. It stretches for over 1,900 miles from the Pacific Ocean in the west to the Gulf of Mexico in the east. The border is marked by a variety of physical features, including mountains, rivers, deserts, and oceans. It also crosses through several major cities, including San Diego, California, and El Paso, Texas. The United States-Mexico border is one of the most important and heavily trafficked borders in the world. It is a major route for trade, immigration, and tourism.