The statutes of some of the States give some light along this line. South Carolina in 1792 prohibited the introduction of slaves either by land or sea.[98] Delaware, however, as early as 1787, passed a law which recites that: "Sundry negroes and mulattoes, as well freeman as slaves, have been exported and sold into other States, contrary to the principles of humanity and justice, and derogatory to the honor of this State." This law prohibited their exportation without a permit.[99] It seems to have been something more than merely incidental for it was amended in 1793, as follows: "That from and after the first Tuesday of October next, the justice of the Court of General Quarter Sessions and Jail Delivery, or any two of them, shall have the like power to grant a licence or permit to export, sell or carry out for sale, any negro or mulatto slave from this State that five justices of the peace in open Sessions now have."[100] We have evidence to show that, by 1802, Alexandria, in the District of Columbia, had become a sort of depot for the sale of slaves, and that men visited it from distant parts of the United States in order to purchase them.[101] About this time slaves were in great demand and very high in Mississippi,[102] and probably, also, in the new States of Kentucky and Tennessee.[103] However, it is not to be supposed that the great increase of the slave population in these sections before 1815 was due, to any great extent, to the domestic slave trade. There were five causes which may be assigned for this increase, of which the domestic trade was, probably, among the least, if not the least. No doubt, the most important was the immigration of slave holders with their slaves.[104] This immigration was considerable: the white population of Tennessee and Kentucky nearly trebled between 1790 and 1800, and between 1800 and 1810 it about doubled, and the population of Mississippi more than quadrupled between 1800 and 1810. Slaves, also, increased in as great a ratio.[105] Second, we consider the South Carolina slave trade from 1804 to 1807 inclusive. From a speech of Mr. Smith of South were sold in the Carolinas, but that the most of Carolina in the United States Senate, December 8, 1820, we learn that only a small part of the negroes introduced in consequence of this trade them were bought by the people of the Western and Southwestern States and territories.[106] Third, was the natural increase. Fourth would be the illegal foreign slave trade,[107] and fifth is the domestic trade. It is impossible to more than approximate the relative importance of these factors.