The variation in income by latitude within Latin America is more striking given that the countries in the region share many common aspects of colonial and cultural history. Two simple facts suggest the magnitude of the economic impacts of geography. Likewise, landlocked countries have an average income per capita of only one-third the income of countries with access to the sea. The economic disadvantage of the tropics can be largely attributed to lower agricultural productivity and a higher burden of disease. Natural disasters, especially hurricanes, probably also play a role, but one that is difficult to quantify for lack of good data.
Agricultural yields depend sensitively on climate and soil resources.
Climate and soil conditions are characteristically different in temperate and tropical ecological zones. Furthermore the tremendous differences in the natural plant and animal communities of the tropics and the temperate zones suggest that the productivity of the narrow range of plants used for agricultural staples would also be systematically different between the two regions. Although it is possible, in principle, for food staples to be adapted to be equally productive in temperate and tropical zones, in practice this has not happened. Even after accounting for differences in input use in agriculture, tropical yields of the main agricultural crops are starkly lower than temperate yields. Here we choose to focus on disease as one of the primary side-effects of geography.