The U.S. Constitution barred the federal government from prohibiting the importation of slaves for twenty years. Various states passed bans on the international slave trade during that period; by 1808, the only state still allowing the importation of African slaves was South Carolina. After 1808, legal importation of slaves ceased, although there was smuggling via Spanish Florida and the disputed Gulf Coast to the west. This route all but ended after Florida became a U.S. territory in 1821 (but see slave ships Wanderer and Clotilda). The replacement for the importation of slaves from abroad was increased domestic production. Virginia and Maryland had little new agricultural development, and their need for slaves was mostly for replacements for decedents. Normal reproduction more than supplied these: Virginia and Maryland had surpluses of slaves. Their tobacco farms were "worn out" and the climate was not suitable for cotton or sugar cane. The surplus was even greater because slaves were encouraged to reproduce (though they could not marry). The pro-slavery Virginian Thomas Roderick Dew wrote in 1832 that Virginia was a "negro-raising state"; i.e. Virginia "produced" slaves. According to him, in 1832 Virginia exported "upwards of 6,000 slaves" per year, "a source of wealth to Virginia". A newspaper from 1836 gives the figure as 40,000, earning for Virginia an estimated $24,000,000 per year. Demand for slaves was the strongest in what was then the southwest of the country: Alabama, Mississippi, and Louisiana, and, later, Texas, Arkansas, and Missouri. Here there was abundant land suitable for plantation agriculture, which young men with some capital established. This was expansion of the white, monied population: younger men seeking their fortune. The most valuable crop that could be grown on a plantation in that climate was cotton. That crop was labor-intensive, and the least-costly laborers were slaves. Demand for slaves exceeded the supply in the southwest; therefore slaves, never cheap if they were productive, went for a higher price. As portrayed in Uncle Tom's Cabin (the "original" cabin was in Maryland), "selling South" was greatly feared. A recently (2018) publicized example of the practice of "selling South" is the 1838 sale by Jesuits of 272 slaves from Maryland, to plantations in Louisiana, to benefit Georgetown University, which has been described as "ow[ing] its existence" to this transaction. Traders responded to the demand, including John Armfield and his uncle Isaac Franklin, who were "reputed to have made over half a