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European settlers introduced another geographical problem that to this day holds many countries back from developing their full potential: they stayed near the coasts, especially (as we saw in Africa) in regions where the interior was infested by mosquitos and disease. Most of the countries' biggest cities, often the capitals, were therefore near the coasts, and all roads from the interior

Just as the geography of the USA helped it become a great power, so that of the twenty countries to the south ensures that none will rise to seriously challenge the North American giant this century nor come together to do so collectively.