or importation of slaves into any of the old thirteen States, and at all
times, under the Constitution, have had power to prohibit such migration
or importation into any of the new States or territories of the United
States. The Constitution contains no express provision respecting
slavery in a new State that may be admitted into the Union; every
regulation upon this subject belongs to the power whose consent is
necessary to the formation and admission of new States into the Union.
Congress may, therefore, make it a condition of the admission of a new
State, that slavery shall be forever prohibited within the same. We may,
with the more confidence, pronounce this to be the true construction
of the Constitution, as it has been so amply confirmed by the past
decisions of Congress.

Although the articles of confederation were drawn up and approved by
the old Congress, in the year 1777, and soon afterwards were ratified by
some of the States, their complete ratification did not take place until
the year 1781. The States which possessed small and already settled
territory, withheld their ratification, in order to obtain from the
large States a cession to the United States of a portion of their vacant
territory. Without entering into the reasons on which this demand was
urged, it is well known that they had an influence on Massachusetts,
Connecticut, New York, and Virginia, which States ceded to the United
States their respective claims to the territory lying northwest of the
river Ohio. This cession was made on the express condition, that the
ceded territory should be sold for the common benefit of the United
States; that it should be laid out into States, and that the States
so laid out should form distinct republican States, and be admitted as
members of the Federal Union, having the same rights of sovereignty,
freedom, and independence as the other States. Of the four States which
made this cession, two permitted, and the other two prohibited slavery.