Politics and culture have more weight than pure geography. Haiti is better described as part of the Caribbean, which like the Pacific Islands, is almost it's own thing. Geographically, it's more North than South American, but that distinction isn't useful for understanding it. The Americas can be broken down into the zones of Central, North, South, and the Caribbean. Culturally, it can best be divided in two as English America and Latin America. The traditional North vs South line betrays how the US and Canada relate to every other American country.

I wish we legally recognized overlap with our geographic categorization. Eastern Europe overlaps with both Europe and Asia. North and South America overlap in Central America and the Caribbean. The Middle East overlaps with Asia, Africa, Western Europe, and Eastern Europe. Regions really aren't exclusive.