Following a period of immense legislative spending in the 1820s and 1830s, the state of Illinois was badly in debt and many believed replacing the original 1818 state constitution would help solve the crisis. The first call for a constitutional convention occurred during the 1842 general election but failed because, although the majority of people who voted on the question approved the convention, they did not constitute the majority of total voters. Illinoisans voted on a second call in 1846 and overwhelmingly approved it. Voters selected delegates the following year, who then assembled in Springfield on June 7. Democrats constituted a slight majority and Newton Cloud, a member of the party, was selected as its president. The convention remained in session until August 31, when it produced a document that effectively represented a compromise between Democrats and Whigs. The new constitution heavily reduced the number of legislators and tightened the residency and age requirements for holding office. In order to curtail state spending, it dramatically reduced legislator salaries and set limits on the acquisition of state loans. Illinois governors were granted veto power but vetoes could be overturned with just a majority legislative vote. The constitution also curtailed government appointments and all state and county positions, including supreme court justices, became elective. A great deal of debate over banks resulted in the new constitution forbidding the creation of state banks but approving the creation of corporations with banking functions.
Slavery was another issue facing the delegates. The Illinois Constitution of 1818 prohibited slavery in most of Illinois, but allowed salt manufacturers to employ African American slave labor on the federal government salt works in Gallatin County. Adult slaves or indentured servants already in the state, moreover, remained in servitude, their children to become free at the age of eighteen. Unlike the Indiana and Ohio constitutions, the Illinois Constitution did not include a clause prohibiting amendment to allow the introduction of slavery, and in 1824 pro-slavery forces tried unsuccessfully to call a constitutional convention to amend the constitution to legalize slavery. Debate within the state over slavery and the status of African Americans mounted during the movement for the constitutional convention, and the debate within the convention over black migration and slavery was also contentious. Delegates ultimately passed an article prohibiting African Americans from immigrating into Illinois and effectively ending any vestiges of slavery in the state.
Illinoisans ratified the new constitution on March 6, 1848, and it took effect on April 1.
Janet Cornelius, Constitution Making in Illinois, 1818-1970 (Urbana: University of Illinois Press, 1972), 25-44; Arthur Charles Cole, ed., The Constitutional Debates of 1847, vol. 14 of Collections of the Illinois State Historical Library, Constitutional Series (Springfield: Illinois State Historical Library, 1919); John A. Metzger, The Gallatin County Saline and Slavery in Illinois (Master's Thesis, Southern Illinois University, 1971), 62-113.