The author of the Kansas-Nebraska bill doubtless anticipated a gradual and natural occupation of the new Territories by settlers like those home-seekers who had taken up government lands in Iowa and other States of the Northwest.  In the course of time, it was to be expected, such communities would form their own social and political institutions, and so determine whether they would permit or forbid slave-labor.  By that rapid, and yet on the whole strangely conservative, American process the people of the Territories would become politically self-conscious and ready for statehood.  Not all at once, but gradually, a politically self-sufficient entity would come into being.  Such had been the history of American colonization; it seemed the part of wise statesmanship to follow the trend of that history.

Theoretically popular sovereignty, as applied in the Kansas-Nebraska Act, was not an advance over the doctrine of Cass and Dickinson.  It professed to be the same which had governed Congress in organizing Utah and New Mexico.  Nevertheless, popular sovereignty had an artificial quality which squatter sovereignty lacked.  The relation between Congress and the people of the Territories, in the matter of slavery, was now to be determined not so much by actual conditions as by an abstract principle.  Federal policy was indoctrinated.

There was, too, this vital difference between squatter sovereignty in Utah and New Mexico and popular sovereignty in Nebraska and Kansas:  the former were at least partially inhabited and enjoyed some degree of social and political order; the latter were practically uninhabited.  It was one thing to grant control over all domestic concerns to a population in esse, and another and quite different thing to grant control to a people in posse.  In the Kansas-Nebraska Act hypothetical communities were endowed with the capacity of self-government, and told to decide for themselves a question which would become a burning issue the very moment that the first settlers set foot in the Territories.  Congress attempted thus to solve an equation without a single known quantity.

Moreover, slavery was no longer a matter of local concern.  Doubtless it was once so regarded; but the time had passed when the conscience of the North would acquiesce in a laissez faire policy.  By force of circumstances slavery had become a national issue.  Ardent haters of the institution were not willing that its extension or restriction should be left to a fraction of the nation, artificially organized as a Territory.  The Kansas-Nebraska Act prejudiced the minds of many against the doctrine, however sound in theory it may have seemed, by unsettling what the North regarded as its vested right in the free territory north of the line of the Missouri Compromise.  The Act made the political atmosphere electric.  The conditions for obtaining a calm, dispassionate judgment on the domestic concern of chief interest, were altogether lacking.