Consider: if you incorporate those tropical countries with the Republic of the United States, you will have to incorporate their people too.

Summary

This quote suggests that if tropical countries were to be integrated into the United States, it would involve incorporating their people as well. It implies that any expansion or integration would require not just the physical territory but also the inclusion and assimilation of the people who inhabit those countries. It raises the point that such a process would involve more than just territorial expansion, but also bringing diverse cultures and populations together.