Missouri Compromise

By Jori Korpershoek

The Missouri Compromise of 1820 was an agreement between the slave owning South and the abolitionist North of the United States of America. Congress drew a line through the American continent and declared that on one side slavery would be legal, on the other side it would be illegal. Acemoglu, Johnson and Robinson look at institutions on the national level, but in this case the level of inclusiveness clearly differed within the nation. Can the same mechanism of higher settler mortality leading to extractive institutions be used to explain these intra-national differences?

When talking about diseases in the New World, the main culprits are usually smallpocks, measles and chickenpox which wiped out a significant percentage of Native Americans. But not all newly imported diseases would be as harmless to the new settlers. Ships from Africa did not only bring slaves, but also carried malaria falciparum, an especially deadly strain of malaria that many West-Africans developed immunity to. 

In "The Colonial Origins of Comparative Development" Acemoglu et al. argue that the higher the mortality rate for Europeans in a colony, the worse its institutions. In his book "1493" Michael C. Mann proposes a similar hypothesis for America. In early colonies where malaria falciparum thrived, death rates for Europeans would be higher than for their immune slaves. These place would in turn rely more heavily on that most ‘peculiar’ extractive institution of African slavery rather than (European) indentured or wage labor.

Mann provides potential evidence that suggests this hypothesis is worth further investigation. Malaria falciparum is very temperature sensitive. The difference between it thriving and not being a problem depends on a temperature difference of a few degrees each winter. In Atlantic City, New Jersey, the mosquitos would die every year. 190 Kilometer south in Washington D.C. the mosquito would survive the slightly warmer winters. Between these cities runs the Mason-Dixon line, which roughly divided the North from the South.