After 1800, cotton and tobacco became important export crops. The eastern half of the state, especially the Tidewater region, developed a slave society based on a plantation system and slave labor. Besides slaves, there were a number of free people of color in the state. Most were descendants from free African Americans who had migrated along with neighbors from Virginia during the 18th century. The majority were the descendants of unions in the working classes between white women, indentured servants or free, and African men, indentured, slave or free. After the Revolution, Quakers and Mennonites worked to persuade slaveholders to free their slaves. Some were inspired by their efforts and the language of the Revolution to arrange for manumission of their slaves. The number of free people of color rose markedly in the first couple of decades after the Revolution. Many free people of color migrated to the frontier, along with their European-American neighbors, where the social system was looser. By 1810, nearly three percent of the free population consisted of free people of color, who numbered slightly more than 10,000. The western areas were dominated by white families, especially Scots-Irish, who operated small subsistence farms. In the early national period, the state became a center of Jeffersonian and Jacksonian democracy, with a strong Whig presence, especially in the western part of the state. After Nat Turner's slave uprising in 1831, North Carolina and other southern states reduced the rights of free blacks. In 1835, the legislature withdrew their right to vote. Southern slave codes criminalized willful killing of a slave in most cases.