This traffic, coupled with the alarm caused by negro insurrections in the West Indies, prepared the public mind for positive action, as the year approached when Congress might constitutionally prohibit the foreign slave trade. The Act of March 2, 1807, however, only partially met the expectations of the anti-slavery people. The African slave trade was forbidden, but negroes illegally imported were to be disposed of as the legislatures of the several States should determine. There was reason to fear that the Southern States would neglect to legislate on this important matter, and that the act would be indifferently enforced. Moreover, the coastwise slave trade for purposes of sale was not interdicted, but forbidden only in vessels under forty tons burden. That the Act of 1807 did not prevent the African slave trade was patent to every one who knew conditions in the Southern Seaboard States; but the extent of this traffic can only be surmised. During the debates on the Missouri Bill, Tallmadge stated that fourteen thousand negroes had been brought into the country within the last year, and the statement was not challenged. When the Missouri controversy was renewed in the session of December, 1819, the number of free States equaled the number of slave States. The addition of a twenty-third State, then, would unsettle the equilibrium between the sections in the Senate. A growing antagonism based upon widely different economic and social organizations was coming to be felt--felt rather than clearly perceived and openly recognized. In the year 1800, the two sections had been nearly equal in population; in 1820, the North outnumbered the South by over half a million. This disparity in numbers had a direct political significance, for the national House of Representatives was beyond all question controlled by the delegations from the free States. No great prescience was needed to warn the South that in self-defense it must maintain the even balance of sections in the Senate. The contest for Missouri was therefore essentially "a struggle for sectional domination." The Tallmadge amendment was passed by the House, but rejected by the Senate, after a heated debate which convinced Southern statesmen that there was a distinct anti-slavery sentiment at the North. The adjournment of Congress threw the whole controversy into the crucible of public opinion. The latent hostility of men and women with humanitarian sympathies was at once raised to white heat. Mass meetings in city, town, and county passed resolutions against the spread of slavery and the admission of more slave States. Yet it can hardly be said that the public conscience was deeply touched. The leaven of abolitionism had to work many years before it could produce results in politics.