The first Illinois Constitution was adopted in 1818 when Illinois was admitted to the Union. Constitutional revisions were ratified in 1848, 1870 and 1970. Important features of the fourth Illinois Constitution include the creation of home rule powers for larger municipalities and other units of local government. The current version of the Illinois Constitution was adopted by special election on December 15, 1970.Cite error: Invalid
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In 1862 a constitutional convention was held, but the changes known as the "Copperhead constitution" were not ratified by the voters. A constitutional convention was held in 1920, but in 1922 the changes were rejected by voters.
Article XIV requires that Illinois voters be asked at least every 20 years if they desire a constitutional convention. 1988 was the last time that measure was put to a vote, so in 2008 Illinois voters will be asked if there is a need for a constitutional convention to revise the state constitution. In 1988 the measure failed 900,109 votes for and 2,727,144 against the measure. 1,069,939 other voters choose neither option.  In 2008 the convention ballot measure failed with 67.4% voting against it. 
- See also: Preambles to state constitutions
The preamble to the Illinois Constitution is:
We, the People of the State of Illinois; grateful to Almighty God for the civil, political and religious liberty which He has permitted us to enjoy and seeking His blessing upon our endeavors — in order to provide for the health, safety and welfare of the people; maintain a representative and orderly government; eliminate poverty and inequality; assure legal, social and economic justice; provide opportunity for the fullest development of the individual; insure domestic tranquility; provide for the common defense; and secure the blessings of freedom and liberty to ourselves and our posterity - do ordain and establish this Constitution for the State of Illinois.
The 1970 Constitution of Illinois has a preamble and 14 articles.
Article 1 is a Bill of rights and contains similar provisions as the United States Bill of Rights, such as freedom of religion, freedom of speech and freedom of assembly. It also contains items not included in the United States Constitution like section 18, which prohibits discrimination based on sex and section 19, which prohibits discrimination based on physical or mental handicaps.
Article 3, Suffrage and Elections, describes voting qualifications, disqualifications and other election rules. Section 1 stipulates that a person must be 18 years old and a resident of the state for 30 days to vote. Section 2 disqualifies persons persons convicted of a felony. Section 4 provides that the Illinois General Assembly establish rules for elections. Section 5 establishes rules for the state board of election, requiring that no political party have a majority on the board.
Article 4, the Legislature, provides rules for the Illinois General Assembly. Section 1 divides the assembly into two bodies, the Illinois Senate with 59 legislative districts and the Illinois House of Representatives with 118 representative districts. Section 2 describes the composition of the two bodies and section 3 describes legislative redistricting procedures. Section 9 describes procedures involving executive vetos of legislation. Section 14 describes impeachment rules.
Article 6, the Judiciary, sets up rules for Supreme Court of Illinois, the Illinois Appellate Court, and the circuit or trial courts of Illinois.
Article 7, Local Government, provides rules for county, township and city governments and provides them with a limited ability to pass ordnances.
Article 8, Finance, provides for financial matters including obligation of funds, budgeting, spending and audits.
Article 9, Revenue, provides rules for various forms of taxation and state debt.
Article 10, Education, establishes the goal of free schooling though secondary education, high school and creates a state board of education.
Article 11, Environment, grants each person the "right to a healthful environment." It sets this as public policy and the duty of individuals to ensure a healthful environment be maintained.
Article 12, Militia, sets rules for the state militia saying, "The State militia consists of all able-bodied persons residing in the State except those exempted by law." It establishes the Governor of Illinois as the commander in chief of the militia and grants authority to use the militia to "enforce the laws, suppress insurrection or repel invasion."
Article 13, General provisions, establishes rules for persons holding public office. Section 7 provides for public transportation, allowing the General assembly to spend money to provide it.
Article 14, Constitutional Revision, describes procedures for amending the constitution of Illinois. Section one describes rules for constitutional conventions.
Amending the constitution
- Main article: Amending state constitutions
Article XIV lays out four different routes that can be taken in order to change the constitution over time.
- A constitutional convention can be held if 60% of the members of both houses of the Illinois General Assembly vote to place such a question on the ballot.
- Every twenty years, the question of whether to hold a convention is automatically referred to a statewide ballot.
- An legislatively-referred constitutional amendment can be proposed if 60% of the members of both houses of the Illinois General Assembly vote to put in on the ballot.
ffice in that election, with some constraints which include:
- The legislature can only propose to amend up to three articles of the constitution in any one election.
- The legislature is not allowed to propose any amendments when a constitutional convention has been called up through the time that an election is held on any proposed amendments or revisions that arise from that convention.
- An initiated constitutional amendment can be proposed but only under conditions including:
- It can only apply to Article IV of the Illinois Constitution.
- Signatures equal to 8% of the total vote cast for governor in the most recent gubernatorial election must be collected.
"* Amendments are "limited to structural and procedural subjects" contained in Article IV.
Whether the question at hand is about holding a constitutional convention, ratifying an amendment proposed by the Illinois General Assembly, or adopting an initiated constitutional amendment, these ballot questions are only considered successful if voters say "yes" by a supermajority vote of 60% of those voting on the question or a majority of those who cast a ballot for any office in that election.
- Illinois Constitution
- Understanding the Illinois Constitution, Illinois State Bar Association.
- Southwestern Illinois College
- Constitution study Guide
- The Illinois Constitution
- Lusk, David W. Politics and Politicians: A Succinct History of the Politics of Illinois (Google Books), H. W. Rokker: 1884, pp. 326–328, and p. 142. Retrieved 18 September 2007.
- Illinois History Teacher, Vol 3:1 1996. Illinois Copperheads & The American Civil War. Illinois Historic Preservation Agency. 1996.
- Illinois Blue Book 2005-2006. Illinois History timeline.
- Constitution of the State of Illinois. Article 14 - Constitutional revisions
- Proposed amendments. 1988 - Proposed call for a Constitutional Convention.
- "New York Times", Illinois Election Results, 12/9/2008