Considering the several States and the citizens of the several States as equals and entitled to equal rights under the Constitution, if this were an original question it might well be insisted on that the principle of noninterference is the true doctrine and that Congress could not, in the absence of any express grant of power, interfere with their relative rights. Upon a great emergency, however, and under menacing dangers to the Union, the Missouri compromise line in respect to slavery was adopted. The same line was extended farther west in the acquisition of Texas. After an acquiescence of nearly thirty years in the principle of compromise recognized and established by these acts, and to avoid the danger to the Union which might follow if it were now disregarded, I have heretofore expressed the opinion that that line of compromise should be extended on the parallel of 36° 30' from the western boundary of Texas, where it now terminates, to the Pacific Ocean. This is the middle ground of compromise, upon which the different sections of the Union may meet, as they have heretofore met. If this be done, it is confidently believed a large majority of the people of every section of the country, however widely their abstract opinions on the subject of slavery may differ, would cheerfully and patriotically acquiesce in it, and peace and harmony would again fill our borders.
The restriction north of the line was only yielded to in the case of Missouri and Texas upon a principle of compromise, made necessary for the sake of preserving the harmony and possibly the existence of the Union.
It was upon these considerations that at the close of your last session I gave my sanction to the principle of the Missouri compromise line by approving and signing the bill to establish "the Territorial government of Oregon." From a sincere desire to preserve the harmony of the Union, and in deference for the acts of my predecessors, I felt constrained to yield my acquiescence to the extent to which they had gone in compromising this delicate and dangerous question. But if Congress shall now reverse the decision by which the Missouri compromise was effected, and shall propose to extend the restriction over the whole territory, south as well as north of the parallel of 36° 30', it will cease to be a compromise, and must be regarded as an original question.