Acemoglu and Robinson on why Haiti remains so desperately poor. I’m not sure I would discount the cultural/David Landes-type arguments quite so quickly, but their institutional story is a compelling one.
One hypothesis about the divergence between Haiti and the Dominican Republic is that a similar situation arose with Haiti and the Dominican Republic. Though the latter shared a history of slavery, dictatorship and US invasion, it did not suffer as much as Haiti. After 1930 Rafael Trujillo, head of the US created national guard, set himself up as dictator. He controlled the army and embarked on a path of extractive economic growth. As the world economy boomed after 1945, divergence set in. The Dominican Republic exported sugarcane and cigars; afterwards they developed a successful export processing zone. After Trujillo was assassinated in 1961, they managed an imperfect transition to more inclusive political institutions, sustaining the economic growth. Haiti was different, without such a strong state or political control of the army, the period after 1930 saw political instability not extractive growth and when François Duvalier (“Papa Doc”) came to power in 1957 he privatized violence using the ton ton macoutes to control the country, not the army. There was no extractive growth in Haiti, just anarchy.