(Taken from Kenneth Stampp, The Causes of the Civil War, pp. 148-49.)
The right to have [slave] property protected in the territory is not a mere abstraction without application or practical value. In the past there are instances where the people of the Southern States might have colonized and brought new slave States into the Union had the principle been recognized, and the Government, the trustee of the Southern States, exercised its appropriate powers to make good for the slaveholder the guarantees of the Constitution . . . When the gold mines of California were discovered, slaveholders at the South saw that, with their command of labor, it would be easy at a moderate outlay to make fortunes digging gold. The inducements to go there were great, and there was no lack of inclination on their part. But, to make the emigration profitable, it was necessary that the [slave] property of Southern settlers should be safe, otherwise it was plainly a hazardous enterprise, neither wise nor feasible. Few were reckless enough to stake property, the accumulation of years, in a struggle with active prejudices amongst a mixed population, where for them the law was a dead letter through the hostile indifference of the General Government, whose duty it was, by the fundamental law of its existence, to afford adequate protection -- executive, legislative, and judicial -- to the property of every man, of whatever sort, without discrimination. Had the people of the Southern States been satisfied they would have received fair play and equal protection at the hands of the Government, they would have gone to California with their slaves. . . . California would now have been a Slave State in the Union. . . .
What has been the policy pursued in Kansas? Has the territory had a fair chance of becoming a Slave State? Has the principle of equal protection to slave property been carried out by the Government there in any of its departments? On the contrary, has not every appliance been used to thwart the South and expel or prohibit her sons from colonizing there? . . . In our opinion, had the principle of equal protection to Southern men and Southern property been rigorously observed by the General Government, both California and Kansas would undoubtedly have come into the Union as Slave States. The South lost those States for the lack of proper assertion of this great principle. . . .
New Mexico, it is asserted, is too barren and arid for Southern occupation and settlement. . . . Now, New Mexico . . . teems with mineral resources. . . . There is no vocation in the world in which slavery can be more useful and profitable than in mining. . . . [Is] it wise, in our present condition of ignorance of the resources of New Mexico, to jump to the conclusion that the South can have no interest in its territories, and therefore shall waive or abandon her right of colonizing them? . . .
We frequently talk of the future glories of our republican destiny on the continent, and of the spread of our civilization and free institutions over Mexico and the Tropics. Already we have absorbed two of her States, Texas and California. Is it expected that our onward march is to stop here? Is it not more probable and more philosophic to suppose that, as in the past, so in the future, the Anglo-Saxon race will, in the course of years, occupy and absorb the whole of that splendid by ill-peopled country, and to remove by gradual process, before them, the worthless mongrel races that now inhabit and curse the land? And in the accomplishment of this destiny is there a Southern man so bold as to say, the people of the South with their slave property are to consent to total exclusion. . . . ? Our people will never sit still and see themselves excluded from all expansion, to please the North.