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History: Missouri Compromise


In an effort to preserve the balance of power in Congress between slave and free states, the Missouri Compromise was passed in 1820 admitting Missouri as a slave state and Maine as a free state. Furthermore, with the exception of Missouri, this law prohibited slavery in the Louisiana Territory north of the 36° 30´ latitude line. In 1854, the Missouri Compromise was repealed by the Kansas-Nebraska Act. Three years later the Missouri Compromise was declared unconstitutional by the Supreme Court in the Dred Scott decision, which ruled that Congress did not have the authority to prohibit slavery in the territories.

  • Missouri Compromise
    From "Statutes at Large, 16th Congress, 1st Session," A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates, 1774 - 1875.



The digital collections of the Library of Congress contain a wide variety of primary source materials associated with the Missouri Compromise, including government documents, manuscripts, and maps. Provided below is a link to the home page for each relevant digital collection along with selected highlights.

Congressional Publications

Missouri Compromise Debate References:

Congress debated the admission of Missouri and Maine from December 1819 to March 1820. Selected references to debate on the Missouri Compromise can be found in the Annals of Congress on the following dates:

  • February 16, 1820
    The Senate agreed to combine the Maine and Missouri bills into one bill by a vote of 23 to 21.
  • February 17, 1820
    The Senate agreed to an amendment offered by Senator Jesse Thomas that prohibited slavery in the Louisiana Territory north of the 36° 30´ latitude line, except for Missouri, and then agreed to the final version of the bill by a vote of 24 to 20.
  • February 23, 1820
    The House of Representatives rejected the Senate's version of the bill.
  • March 1, 1820
    The House of Representatives passed its own bill, which admitted Missouri without slavery, by a vote of 91 to 82.
  • March 2, 1820
    A House-Senate conference agreed to the Senate's version of the bill.
  • March 2, 1820
    The House voted 90 to 87 to allow slavery in Missouri.
  • March 2, 1820
    The House voted 134 to 42 to prohibit slavery in the Louisiana Territory north of the 36° 30´ latitude line.
  • March 6, 1820
    President James Monroe signed the Missouri Compromise.

American State Papers:

The American State Papers contain the legislative and executive documents of Congress during the period 1789 to 1838. References in the American State Papers to the Missouri Compromise include:

Andrew Jackson Papers

  • Andrew Jackson Papers
    The Andrew Jackson Papers contain more than 26,000 items dating from 1767 to 1874. Included are memoranda, journals, speeches, military records, land deeds, and miscellaneous printed matter, as well as correspondence. References to the Missouri Compromise include:
  • John Henry Eaton to Andrew Jackson, March 11, 1820
    Excerpt: "The President says he has recvd your letter. He said he wanted to have with me some conversation in relation to it, but it being a levee evening and much crowded no oppertunity was then had. He desired me to say to you, that he had been so taken up with the deep agitations here the (missouri bill), that he did not [have] time but that he would shortly write to you. The agitation was indeed great I assure you—dissolution of the Union had become quite a fimiliar subject. By the compromise however restricting slavery north of 36½ degrees we ended this unpleasant question. Of this the Southern people are complaining, but they ought not, for it has preserved peace dissipated angry feelings, and dispelled appearances which seemed dark and horrible and threat[en]ing to the interest and harmony of the nation. The constitution has not been surrendered by this peace offering, for it only applies while a territory when it is admitted congress have the power and right to legislate, and not when they shall become States"
  • Excerpt: "I perceive you have strong foreboding as to our future policy. The discussion on the Missouri question has undoubtedly contributed to weaken in some degree the attachment of our southern and western people to the Union; but the agitators of that question have, in my opinion, not only completely failed; but have destroyed to a great extent their capacity for future mischief. Should Missouri be admitted at the next session, as I think she will without difficulty, the evil effects of the discussion must gradually subside."
  • Caldwell Calhoun to Andrew Jackson, June 1, 1820

James Madison Papers

  • James Madison Papers, 1723 to 1859
    The James Madison Papers from the Manuscript Division at the Library of Congress consist of approximately 12,000 items captured in some 72,000 digital images. Search Madison's Papers to find additional letters discussing the Missouri Compromise. References to the Missouri Compromise include:
  • James Madison to Robert Walsh, November 27, 1819. Missouri Controversy.
    Excerpt: "On the whole, the Missouri question, as a constitutional one, amounts to the question whether the condition proposed to be annexed to the admission of Missouri would or would not be void in itself, or become void the moment the territory should enter as a State within the pale of the Constitution. And as a question of expediency & humanity, it depends essentially on the probable influence of such restrictions on the quantity & duration of slavery, and on the general condition of slaves in the U. S."
  • James Madison to James Monroe, February 10, 1820.
    Excerpt: "It appears to me as it does to you, that a coupling of Missouri with Maine, in order to force the entrance of the former thro' the door voluntarily opened to the latter is, to say the least, a very doubtful policy..."
  • James Madison to James Monroe, February 23, 1820.
    Excerpt: "The pinch of the difficulty in the case stated seems to be in the words "forever," coupled with the interdict relating to the Territory N. of L 36° 30'. If the necessary import of these words be that they are to operate as a condition on future States admitted into the Union, and as a restriction on them after admission, they seem to encounter indirectly the argts. which prevailed in the Senate for an unconditional admission of Missouri."

James Monroe Papers

  • James Monroe Papers
    The James Monroe Papers at the Manuscript Division of the Library of Congress consist of approximately 5,200 items dating from 1758 to 1839. Monroe (1758–1831) was the fifth president of the United States, and one of 23 presidents whose papers are at the Library of Congress. References to the Missouri Compromise include:
  • President James Monroe's notes, February 13, 1820, on the Missouri Compromise
    Excerpt: "The idea was that if the whole arrangement, to this effect, could be secured, that it would be better to adopt it, than break the union. Neither did Mr. Barbour, nor any other person alluded to, favor this, but to save the union, believing it to be in imminent danger."

The following reliable websites contain primary source materials and related information on the Missouri Compromise.