I remember reading how Haiti was the most valuable new world colony for France, as they were the main producer of sugar in the Americas(?). If they were such a agricultural power house, why didn't they thrive when trading with countries such as the U.S., England, Spain or Portugal.
Anyone can correct me if i'm way offbase (or add anything I've missed), but this is what I've learned from my visits to Haiti.
First, directly after the revolution France strong armed the recently freed slaves into signing a reparations deal which amounted to 90m Francs (some sources differ). This equates to about 17+ billion dollars today, basically France charged Haiti for the lost of revenue from slavery. Haiti wasn't able to finishing pay this debt til about the 1950s, so it was a massive shot to the economy for a very long time. And still Haitians face the repercussions of having to pay this debt today.
They were also put in a tough position because USA still had slavery at the time. Free black people threatened the institution of slavery within USA, so United States backed the reparations placed by France and further placed trade embargoes on Haiti. This further crippled the economy, they basically had no one to trade to for years.
Furthermore in the early 20th century, USA invaded Haiti and many other Latin American countries. They stayed for about 20 years and in that time collected taxes, they destroyed farming that occurred in the north. They massacred animals especially pigs that were essential to Haitian farming etc and introduced these massive farm animals that Haitian Farmers could not support. As well as killing many Haitians who rebelled against the US Military as they marched to the Capital of Haiti.
I know i'm missing a section about how USA altered the Haitian government (constitution, structure etc) but i don't have a good grasp on that yet.
Then in the 1950s Papa Doc and later his son, two American backed dictators, came to be president. Both very corrupt, siphoned money from the already struggling country. Papa Doc created the Tonton Macoutes who basically terrorized the populace for years and his son furthered the use of the Macoutes to instill fear.
I could go on its a long history of abuse, corruption. Its really sad what has happened to the country of Haiti.
Here's a few sources, I've found. But mostly this is just from my visits to Haiti and the from Interactions I have had with people I have done some work with in Haiti.