Indeed, so great was the demand for slaves at this time that the advisability of reopening the African slave trade became one of the principal topics of discussion in Southern Agricultural and Commercial Conventions.[171] In fact, the Vicksburg Convention, 1859, passed a resolution in favor of reopening the African trade.[172]
The New Orleans newspapers during all this period give evidence of the domestic trade. It was very common during the shipping season to see advertisements to the effect that the subscriber, a negro trader, had received, or had just arrived from Virginia, Maryland, the Carolinas or elsewhere, with a large lot of negroes which were offered for sale. Usually the number would be given as fifty, seventy-five, or even a hundred. This would be qualified by the statement that they would be constantly receiving fresh lots. The same advertisement would continue in the same paper for months and even years. Sometimes half a dozen of these could be found in a single issue of a paper. It would be impossible even to approximate from this source the number sold during any given time, for it is likely the number offered for sale bore but little relation to the actual number sold. The States of Maryland, Virginia and the Carolinas were most conspicuous in these advertisements.[173]
Writers on the subject seem to be pretty well agreed that during this period, or during the fifties, about 25,000 slaves were annually sold South from the Northern slave States.[174]
It is interesting to notice in this connection what the Census Reports have to show. But in reading it should be remembered that no account is taken of the sale of slaves except as they took place between the buying and selling States. So the sale of slaves between Virginia and Maryland are not indicated nor those between Mississippi and Alabama.
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.
By 1850, the buying States had another increase of 478,000 and the selling States 180,000. Total increase from 1840 to 1850, 658,000.[186] Deducting 50,000 illicitly imported,[187] we have 606,000 or about 24 per cent. total increase. Accordingly the selling States should have a natural increase of 326,000. Deducting the actual number we have left 146,000, which must have been transported. Deducting three-fifths on account of emigration, there would remain about 58,000 or nearly 6,000 per year for the domestic trade.
Adding Texas to the buying States in 1850, they then have 1,663,000, and in 1860 2,296,000, or an increase of 633,000 during the decade. And the selling States 1,541,000 and 1,657,000 respectively, being an increase of 116,000. Total increase 749,000.[188] Deducting 70,000 which were brought in by illicit trade[189] we have a remainder of 679,000 or 21 per cent. natural increase. From natural increase selling States should have had 207,000 more than the actual. Deducting three-fifths on account of emigration leaves a little more than 8,000 per year sold South annually for these ten years.
It is very probable that the emigration to the cotton States fell off during the fifties owing to the great prosperity in the border States, and it might be fair to reduce the number estimated to have been carried South by emigration to one-third or one-half, which would leave ten or twelve thousand per year for the domestic slave trade.