What ocean borders the East Coast of the United States?

The Atlantic Ocean is the body of water that borders the East Coast of the United States. It runs alongside numerous states from Maine in the northeast down to Florida in the southeast. The Atlantic Ocean is significant not only for its geographical relevance but also for its historical importance to the United States, serving as a major route for exploration, trade, and cultural exchange. The ocean's proximity to the East Coast has played a vital role in the development of major cities such as New York, Boston, and Miami, which are all located along its shores.

The other options refer to different bodies of water that do not border the East Coast of the U.S. The Gulf of Mexico lies to the south of the U.S., bordering states like Texas, Louisiana, Mississippi, Alabama, and Florida, but does not serve as the eastern border. The Southern Ocean encircles Antarctica and is not relevant to the U.S. geographical context. The Arctic Ocean is located to the far north and does not border the East Coast either, focusing instead on northern states like Alaska. Thus, the Atlantic Ocean is the correct and appropriate choice.