The first clause quoted was intended to enable Congress to prohibit the introduction of slaves after the year 1808, and this was promptly done. The second provision was intended to authorize the recapture of slaves escaping from their owners to another state. It was the general expectation of the framers of the constitution that under its provisions slavery would be gradually abolished by the acts of the several states where it was recognized.
The first great controversy that grew out of slavery was whether Missouri should be admitted into the Union as a slave state, and whether slavery should exist in the western territories.
The following provision became part of the law of March 6, 1820, approved by President James Monroe, and known as the compromise measure of that year:
"That, in all that territory ceded by France to the United States under the name of 'Louisiana,' which lies north of 36 deg. 30 min. north latitude, not included within the limits of the state contemplated by this act, slavery and involuntary servitude, otherwise than in the punishment of crimes whereof the party shall have been duly conviced, shall be and is hereby, forever prohibited: Provided, always, That any person escaping into the same, from whom labor or service is lawfully claimed in any other state of territory of the United States, such fugitive may be lawfully reclaimed, and conveyed to the person claiming his or her labor or service, as aforesaid."
This compromise measure fixed the boundary line between free and slave states in all the territories then belonging to the United States. Slavery was thus forever prohibited within the Territories of Kansas and Nebraska. This happy solution was regarded as something more than a mere enactment of Congress. It was a territorial division between the two great sections of our country, acquiesced in by both without question or disturbance for thirty- four years. The memorable controversy that arose in the 31st Congress in 1850 in respect to the territory acquired from Mexico did not in the least affect or relate to the Territories of Nebraska and Kansas. The subject-matter of the several bills originally embraced in Mr. Clay's report of the committee of thirteen, defined the northern boundary of the State of Texas on the line of 36 deg. 30 min. north latitude, provided for the addition of the State of California, for territorial governments for New Mexico and Utah, and for the surrender of fugitive slaves.
In the resolution annexing Texas to the United States there is this express recognition of the Missouri Compromise line:
"New states of convenient size, not exceeding four in number, in addition to said State of Texas, and having sufficient population, may hereafter, by the consent of the said state, be formed out of the territory thereof, which shall be entitled to admission under the provisions of the Federal constitution; and such states as may be formed out of that portion of said territory lying south of 36 deg. 30 min. north latitude, commonly known as the Missouri Compromise line, shall be admitted into the Union with or without slavery, as the people of each state asking admission may desire."
The convention providing for the admission of California expressly stipulated by a unanimous vote that slavery should be forever prohibited in that state. The bill providing for a territorial government for New Mexico, the great body of the territory which lay south of the parallel of latitude 36 deg. 30 min., provided, "That, when admitted as a state, the said territory, or any portion of the same, shall be received into the Union, with or without slavery, as their constitution may prescribe at the time of their admission."
The act organizing the Territory of Utah, lying entirely north of the 37th degree of latitude, contains no provision recognizing the right of the people of that territory to permit slavery within its borders. The situation of the state and its population precluded the possibility of establishing slavery within its borders.
It will be perceived by the compromise measures of 1820 and 1850, the existence or prohibition of slavery was fixed by express laws, or by conditions which it was fondly believed defined the limits of slavery, and thus set at rest the only question that threatened the union of the states. This settlement was indorsed and ratified by the two great parties in their national platforms of 1852, with the solemn pledge of both parties that they would resist the re- opening of these questions.