blacks, and the white population declined further to 16,888 by 1715. Due to the increased implementation of slave codes, which emphasized differential treatment between Africans, and the white workers and ruling planter class, the island became increasingly unattractive to poor whites. Black or slave codes were implemented in 1661, 1676, 1682, and 1688. In response to these codes, several slave rebellions were attempted or planned during this time, but none succeeded. Nevertheless, poor whites who had or acquired the means to emigrate often did so. Planters expanded their importation of African slaves to cultivate sugar cane. One early advocate of slave rights in Barbados was the visiting Quaker preacher Alice Curwen in 1677: "For I am persuaded, that if they whom thou call'st thy Slaves, be Upright-hearted to God, the Lord God Almighty will set them Free in a way that thou knowest not; for there is none set free but in Christ Jesus, for all other Freedom will prove but a Bondage." By 1660, Barbados generated more trade than all the other English colonies combined. This remained so until it was eventually surpassed by geographically larger islands like Jamaica in 1713. But even so, the estimated value of the Colony of Barbados in 1730–1731 was as much as £5,500,000. Bridgetown, the capital, was one of the three largest cities in English America (the other two being Boston, Massachusetts and Port Royal, Jamaica.) By 1700, the English West Indies produced 25,000 tons of sugar, compared to 20,000 for Brazil, 10,000 for the French islands and 4,000 for the Dutch islands. This quickly replaced tobacco, which had been the island's main export. As the sugar industry developed into its main commercial enterprise, Barbados was divided into large plantation estates that replaced the smallholdings of the early English settlers. In 1680, over half the arable land was held by 175 large planters, each of whom used at least 60 slaves. The great plantation ownershad connections with the English aristocracy and great influence on Parliament. (In 1668, the West Indian sugar crop sold for £180,000 after customs of £18,000. Chesapeake tobacco earned £50,000 after customs of £75,000). So much land was devoted to sugar that most foods had to be imported from New England. The poorer whites who were moved off the island went to the English Leeward Islands, or especially to Jamaica. In 1670, the Province of South Carolina was founded, when