The panic of 1837 caused a falling off in the domestic slave trade, and the low price of cotton which continued until 1846[155] hindered its revival. The falling off in the trade is shown by the fact that the per cent. of increase in the slave population of the cotton States was scarcely half as great between 1840 and 1850 as during the previous decade.[156] The slave trade, however, seems to have become brisker in 1843, for while only 2,000 slaves are said to have been sold in Washington in 1842, in 1843, 5,000 were sold there.[157] It does not necessarily follow, however, that all these were sent South. The increased number of sales was caused by two things: the decline in the price of tobacco,[158] and the renewed activity in the sugar industry incident upon a new duty on sugar.[159] This gave rise to a demand for slave labor upon the sugar plantations of the South, but it was a very limited demand. During this period the decline in the value of slaves was great in some States,[160] and it appears very probable there was a general depreciation in value. However, before 1850 three important things had happened, each of which had an effect upon the slave trade. First, the admission of Texas, December, 1845; second, the gradual increase in the price of cotton after 1845; third, the discovery of gold in California. The first opened a large cotton country to development and the required slave labor could be legally supplied only from the United States. The rise in cotton which continued almost uniformly until 1860[161] caused a new impetus to be given to its culture, and the discovery of gold in California infused new life into all the channels of trade. In a few years, indeed, after 1845, the demand for slaves seems to have been greater than the supply. A writer in the "Richmond Examiner," in 1849, says: "It being a well ascertained fact that Virginia and Maryland will not be able to supply the great demand for negroes which will be wanted in the South this fall and next spring, we would advise all who are compelled to dispose of them in this market to defer selling until the sales of the present crop of cotton can be realized as the price then must be very high owing to two reasons: First, the ravages of the cholera, and secondly, the high price of cotton."[162] Indeed, during the fifteen years prior to 1860 the demand for slaves became so great that it caused an increase of one hundred per cent. in their price.[163] However, there was not a great increase in the domestic slave trade. According to a custom house report there were shipped from Baltimore in a little less than two years, in 1851 and 1852 only 1,033 negroes.[164] This is certainly not a large showing though it is probable a great many were sent overland to the South from this place during the same time.