From 1775 until 1861 the vast majority of political maneuvering in the United States involved some facet of the slavery question. The politics of slavery had become the main show on the political stage.
First and foremost, the southern Founders had insisted on a number of protections in the Constitution that allowed the importation of slaves to continue unabated for 20 after the ratification of the founding document. From 1788 until 1808, slaves were imported at a greater rate than at any other time in American history. In addition, another clause in the Constitution prohibited citizens from providing assistance to escaping slaves and required the return of chattel property to owners.
The most famous of the compromises that the Founders agreed upon was the three-fifths compromise. Despite not allowing slaves to vote or exercise any of the other privileges of citizenship, the southern Founders wanted them to be counted for Congressional representation and in the Electoral College. The northern Founders balked at this brazen power grab and refused. It appeared that the issue might destroy any efforts to unite the country.
The delegates arrived at an agreement to count “all other persons” as three-fifths of a person for voting and representation purposes. James Madison came up with the ratio after proposed compromises of 1/2 by Benjamin Harrison of Virginia and 3/4 by several New Englanders failed to gain sufficient support.
This key compromise was to give the slave-holding states a much stronger position in the House of Representatives due to the disproportionate representation of slaveholding states relative to voters. For example, in 1793 slave states would have been apportioned 33 seats in the House of Representatives had the seats been assigned based on the free population; instead they were apportioned 47. In 1812, slaveholding states had 76 instead of the 59 they would have had; in 1833, 98 instead of 73. As a result, southerners dominated the Presidency, the Speakership of the House, and the Supreme Court in the period prior to the Civil War.
According to historian James Oliver Horton, “in the 72 years between the election of George Washington and the election of Abraham Lincoln, 50 of those years [had] a slaveholder as president of the United States, and, for that whole period of time, there was never a person elected to a second term who was not a slaveholder.”
The inevitable growth of the United States westward brought about the movement of slavery from the lowlands of the East to the Mississippi Valley and into the Trans-Mississippi regions of the West. Historians have estimated that one million slaves were moved westward and southward between 1790 and 1860.
Most of these slaves had originated in Maryland, Virginia and the Carolinas. Changes in agriculture had decreased the need for slaves in these states. Before 1810, primary destinations were Kentucky and Tennessee, but after 1810 Georgia, Alabama, Mississippi, Louisiana and Texas received the most slaves. Kentucky and Tennessee became exporting states.
The next major fight on the American political stage was the expansion of slavery into the territories of the former Louisiana Territory and those further west. The main objective was to maintain a balance between slave states and free states. It began with a bill that was introduced in the House in 1819 to allow the Missouri Territory to draft a constitution and form a government preliminary to admission into the Union.
James Tallmadge of New York offered an amendment (named the Tallmadge Amendment), that forbade further introduction of slaves into Missouri, and mandated that all children of slave parents born in the state after its admission should be free at the age of 25. It was passed by the committee and incorporated in the bill which passed the House. The Senate did not concur and the bill died.
In the next session, the issue of Missouri still remained. An amendment, introduced on January 26, 1820 by John W. Taylor of New York, allowing Missouri into the union as a slave state. The question had been complicated by the admission in December of Alabama, a slave state, making the number of slave and free states equal. In addition, there was a bill in passage through the House (January 3, 1820) to admit Maine as a free state.
The Senate decided to connect the two measures. It passed a bill for the admission of Maine with an amendment enabling the people of Missouri to form a state constitution. Before the bill was returned to the House, a second amendment was adopted on the motion of Jesse B. Thomas of Illinois, excluding slavery from the Missouri Territory north of the parallel 36°30′ north (the southern boundary of Missouri), except within the limits of the proposed state of Missouri.
The two houses were at odds not only on the issue of slavery, but also on the parliamentary question of the inclusion of Maine and Missouri within the same bill. The conference committee recommended the enactment of two laws, one for the admission of Maine, the other an enabling act for Missouri. They recommended against having restrictions on slavery but for including the Thomas amendment. Both houses agreed, and the measures were passed on March 5, 1820, and ratified by President James Monroe on March 6.
The question of the final admission of Missouri came up during the session of 1820–1821. The struggle was revived over a clause in Missouri’s new constitution (written in 1820) requiring the exclusion of “free negroes and mulattoes” from the state. Through the influence of Henry Clay, an act of admission was finally passed, upon the condition that the exclusionary clause of the Missouri constitution should “never be construed to authorize the passage of any law” impairing the privileges and immunities of any U.S. citizen. This deliberately ambiguous provision is sometimes known as the Second Missouri Compromise.