Which part of the world did the United States intervene most by sending troops in the nineteenth century?

In the nineteenth century, the United States sent troops into Latin America and South America.

Explanation:

After the Monroe Doctrine, there was a growing political thought in the United States that viewed South American countries as their 'Backyard'

Mexico, Brazil and even newly Independent countries of the time such as Chile and Venezuela were seen as improvised and underdeveloped.

The US political elites held racist views for these countries and assumed that they were poor simply because of an inferior race.

For the next 100 years, the United States would be heavily involved in these countries, either by going directly to war, supporting local rebels or even dictators.