We may pass to the year 1820, when an enactment was passed by Congress
which for thirty-four years thereafter might be regarded as hardly less
fundamental than the Constitution itself. Up till then nine new States
had been added to the original thirteen. It was repugnant to principles
still strong in the North that these States should be admitted to the
Union with State Constitutions which permitted slavery. On the other
hand, it was for two reasons important to the chief slave States, that
they should be. They would otherwise be closed to Southern planters who
wished to migrate to unexhausted soil carrying with them the methods of
industry and the ways of life which they understood. Furthermore, the
North was bound to have before long a great preponderance of population,
and if this were not neutralised by keeping the number of States on one
side and the other equal there would be a future political danger to
slavery. Up to a certain point the North could with good conscience
yield to the South in this matter, for the soil of four of the new slave
States had been ceded to the Union by old slave States and slave-holders
had settled freely upon it; and in a fifth, Louisiana, slavery had been
safeguarded by the express stipulations of the treaty with France, which
applied to that portion, though no other, of the territory then ceded.
Naturally, then, it had happened, though without any definite agreement,
that for years past slave States and free States had been admitted to the
Union in pairs. Now arose the question of a further portion of the old
French territory, the present State of Missouri. A few slave-holders
with their slaves had in fact settled there, but no distinct claims on
behalf of slavery could be alleged. The Northern Senators and members of
Congress demanded therefore that the Constitution of Missouri should
provide for the gradual extinction of slavery there. Naturally there
arose a controversy which sounded to the aged Jefferson like "a fire-bell
in the night" and revealed for the first time to all America a deep rift
in the Union. The Representatives of the South eventually carried their