New York grew in importance as a trading port while under British rule in the early 1700s. It also became a center of slavery, with 42% of households holding slaves by 1730, more than any other city other than Charleston, South Carolina. Most slaveholders held a few or several domestic slaves, but others hired them out to work at labor. Slavery became integrally tied to New York's economy through the labor of slaves throughout the port, and the banks and shipping tied to the South. Discovery of the African Burying Ground in the 1990s, during construction of a new federal courthouse near Foley Square, revealed that tens of thousands of Africans had been buried in the area in the colonial years.