Texas. Angling for position as a power-broker at the upcoming Democratic convention, Walker offered carefully crafted arguments for the annexation of Texas that he hoped would satisfy all interest groups within the Democratic party - including northerners who stood steadfastly against admitting Texas into the Union. A new slave state in the Southwest, Walker reasoned, would draw off unwanted slaves from those areas where the institution was declining, which would be both a boon to slaveholders and a relief to free-soilers who feared the northern migration of millions of free blacks. Ultimately, slavery would also recede in Texas, but Walker predicted that free blacks would move across the Rio Grande, to comingle with other dark-skinned races, thereby restoring the Anglo-Saxon purity of the United States. Ingenious in its design but specious in its logic, Walker's letter caused a sensation and was widely distributed throughout the United States. Thomas R. Hietala, Manifest Design: Anxious Aggrandizement in Late Jacksonian America, 26-33; Frederick Merk, Fruits of Propaganda in the Tyler Administration, 95-120, 221-246.

     14. Defenders of slavery had long maintained that physiological and mental deficiencies destined Africans to a life of bondage. This ethnological argument received support from an unexpected source with the controversial Census of 1840. Apologists of the "peculiar institution" were quick to point out that whereas the Census discovered no appreciable difference between the mental health of northern and southern whites it found that the rate of mental disease among free blacks in the North was eleven times higher than it was among slaves. Opponents of slavery rejected the findings, citing numerous factual errors and cases of false data-collecting. A study of the report revealed broad discrepancies between state and federal census data, the latter often citing mental deficiencies among blacks in towns that, according to state records, contained no black residents at all. Furthermore, critics have since noted the absence of institutional facilities for Negroes in the southern states, making the enumeration of mentally ill slaves difficult, if not impossible. Even if treatment was available, slaveowners seem to have made the decision to institutionalize their chattel only in the most extreme cases, reluctant to be deprived of a slave's labor or bear the burden of hospital costs. Despite the unreliability of the figures, proslavery advocates continued to point to the Census of 1840 as evidence of the dangers of emancipation. Hietala, Manifest Design, 28-39, passim; George Rosen, "The First U.S. Census of the Insane (1840) and Its Use As Pro-Slavery Propaganda," Bulletin of the History of Medicine, 469-483.