What were the permanent long-term US objectives in Latin America before 1898?

I would argue that the permanent US objective in Latin
America was to keep the area stable and unthreatening to the US.  This can be seen
particularly in the Monroe Doctrine.

The Monroe Doctrine
said that European countries should not try to take any new colonies in the Americas. 
It said that any European interference in the affairs of the Latin American countries
would be deemed a threat to the security of the US.  By saying this, the US was
essentially arguing that Latin America was its own sphere of influence and that anything
that happened there was important to the US.

By creating
the Monroe Doctrine, the US made clear that it valued stability in Latin America and it
wanted to keep any potential European enemies from gaining a foothold in the
region.