Although slavery became the bedrock foundation of Virginia's antebellum plantation economy, it started slowly in the first 50 years of the seventeenth century. In 1700, enslaved Africans numbered only about 8 percent of the colony's population. Most of them worked as agricultural laborers on tobacco farms, often along side white indentured servants. When the supply of indentured servants decreased in the eighteenth century, Virginia planters stepped up the importation of enslaved Africans, and by mid-century 2 of every 5 residents were African or African Americans. Some historians contend that whites brought in more and more enslaved Africans after Bacon's Rebellion in 1676 as a means of cutting back on the influx of white indentured servants from England, whom the planters found difficult to control. By the 1790s, what with the onset of soil exhaustion, many white slaveholders in the state found a thriving market for the offspring of their slaves in the growing cotton regions of the lower South. The state's capital, Richmond became a slave depot for gathering slaves to be transported to slave markets in New Orleans and Natchez, Mississippi. Some of these enslaved people were taken via water from Norfolk while others traveled over land in slave coffles. Although other slave states replaced Virginia as the leading concentration of enslaved people, white Virginians remained deeply committed to the institution of slavery. When the southern slaveholding states seceded from the Union, the city of Richmond became the capital of the Confederacy. The state's western region, which was largely populated by non-slaveholding whites, remained loyal to the Union and became the state of West Virginia in 1863.