What type of borders form the boundaries of the United States?

Question

Quizplus · Accepted Answer

The United States has two natural borders: to the north with Canada (the 49th parallel for much of it) and to the south with Mexico (the Rio Grande). The east and west boundaries are coastlines (Atlantic Ocean and Pacific Ocean, respectively), which are also considered natural borders. Thus, all of the U.S. borders can be considered natural, making the initial explanation incorrect. The correct interpretation should be that the United States is bordered by natural features on all sides, including its northern and southern borders with Canada and Mexico, respectively, as well as its eastern and western coastlines along the Atlantic and Pacific Oceans.

What Type of Borders Form the Boundaries of the United