This transportation of negroes from the border States to the South and Southwest from about 1826 to 1832 may be partly accounted for by the probable falling off in the illicit importations[129] and by the fact that cotton and tobacco, which were the staples of some of the border States, were comparatively low in price,[130] making them very unprofitable crops to cultivate in these States. The cotton raised in North Carolina and Virginia decreased almost half during this time.[131] While it appears as if the lower price of cotton merely had the effect in the new States to increase the acreage in order to make up for the deficiency in price. In the new States there was a wonderful increase in production during this period.[132] Slaves, therefore, were of much less productive value in the border States, while in the new States the demand for them was scarcely lessened. The "New Orleans Mercantile Advertiser," of January 21, 1830, says: "Arrivals by sea and river, within a few days, have added fearfully to the number of slaves brought to this market for sale. New Orleans is the complete mart for the slave trade--and the Mississippi is becoming a common highway for the traffic."[133] In the summer of 1831, New Orleans imported 371 negroes in one week, nearly all of whom were from Virginia.[134] In the same year, August 1831, an insurrection of slaves, in which a number of white people were murdered, occurred in Southampton County, Virginia.[135] This caused much excitement throughout the slave States. It opened the eyes of the people to the danger of a large slave population. It seemed, for a while, that it would have a very detrimental effect upon the domestic slave trade, for several importing States began to consider the advisability of prohibiting the further introduction of slaves. Two of the largest importing States,[136] indeed, passed such laws: Louisiana, which, in March, 1831, had repealed her law regulating the importation of slaves[137] in November of the same year, at an extra session of her legislature enacted a law against their importation for sale.[138] And, in January, 1832, Alabama followed suit.[139] The Virginia Legislature of 1831-2, also took up the question of slavery and with open doors vigorously discussed methods of emancipation, and of getting rid of the negro population. It was recognized that the value of slaves in Virginia depended greatly upon the Southern and Western markets. It was feared that other buying States would follow the lead of Louisiana, thus cutting off the outlet of Virginia's surplus slaves, and while the whites were constantly emigrating, the rapidly increasing black population would tend to become congested in the State, producing a condition of society alarming to contemplate.[140]