Slave ownership was the primary marker of class and even the town's freedmen and free people of color typically kept slaves if they had the wealth to do so. Visitors commonly remarked on the sheer number of blacks in Charleston and their seeming freedom of movement, though in fact—mindful of the Stono Rebellion and the violent slave revolution that established Haiti—the whites closely regulated the behavior of both slaves and free people of color. Wages and hiring practices were fixed, identifying badges were sometimes required, and even work songs were sometimes censored. Punishment was handled out of sight by the city's workhouse, whose fees provided the municipal government with thousands a year. In 1820, a state law mandated that each act of manumission (freeing a slave) required legislative approval, effectively halting the practice.