For what reasons did the US have interest in building a canal in South America?

The main reason why the Americans wanted the Panama Canal built was to cut travel time from the Atlantic to the Pacific Oceans.

Explanation (if you need it) :

The Panama Canal was inaugurated in 1914. Its construction had been started by the French, and when they abandoned the project, the Americans took it in 1903.

The intention of Theodore Roosevelt's government was to shorten travel time and distances between the two coasts of the United States, while creating a fast and accessible connection between both oceans, which would allow America to compete more easily in trade international, also giving a greater capacity to react to the Navy in case of a war.

Until that moment, the sea route that connected both oceans was around the Strait of Magellan, with which the American ships had to surround all South America to get from one ocean to the other.

yes

explanation:

why

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.