The slave population of Alabama, Arkansas, Georgia, Louisiana, Mississippi, South Carolina, Tennessee and Missouri in 1820 was in round numbers 644,000, in 1830 997,000 being an increase of 353,000. The slave population in the selling States of Virginia, Maryland, Delaware, North Carolina, Kentucky and the District of Columbia at the same periods[175] was 873,000 and 993,000 respectively, being an increase in these States of 120,000. Total increase of slaves in both sections during the decade, 473,000, from which we deduct 50,000 due to the illicit foreign traffic,[176] leaving 423,000 from natural increase or about 28 per cent. Had the selling States increased at this ratio, instead of 120,000 their increase would have been 244,000. This would seem to indicate that at least 12,400 annually were carried South during this decade. However, only the smaller part of these, and those of the following decade as well, were transported through the operation of the domestic slave trade. Mr. P.A. Morse, of Louisiana, writing in 1857, says that the augmentation of slaves within the cotton States was caused mostly by the migration of slave owners.[177] The "Virginia Times," in 1836, says of the number of slaves exported during the preceding twelve months "not more than one-third have been sold, the others having been carried by their owners who have removed."[178] We conclude from these and other sources[179] that at least three-fifths of the removals of slaves from the border slave States to those farther South from 1820 to 1850 were due to emigration.[180] Thus it is shown that probably 5,000[181] slaves were annually exported by the selling States from 1820 to 1830 by means of the domestic trade. In the next decade adding Florida to the buying State and transferring South Carolina[182] and Missouri[183] to the selling list, we find that in 1830 and in 1840 the buying States had 672,000 and 1,127,000 respectively, being an increase of 455,000; while for the same periods the selling States had 1,333,000 and 1,361,000, being an increase of 28,000. The whole increase, therefore, was 483,000,[184] deducting 40,000 due to illicit foreign trade,[185] we have 443,000 or about 22 per cent. as the natural increase. Had the selling States increased at same rate it would have been 293,000 for the decade. Deducting 28,000 we find that 265,000 can be accounted for only as having been exported. Deducting three-fifths for emigration we have, removing 106,000 for the domestic traffic, an average of 10,600 per year.