ST. LOUIS, MO – August 23, 2026 (STL.News) Missouri Constitution – Constitution Day will be observed September 17, commemorating the signing of the U.S. Constitution in Philadelphia in 1787. For Missourians, the occasion also provides an opportunity to examine a document much closer to home — the Missouri Constitution.
September 17 is not the anniversary of adopting Missouri’s current Constitution. The date commemorates the signing of the federal Constitution. The Missouri Press Association, however, has used Constitution Day as an opportunity to encourage Missourians to learn about their own state Constitution through educational material titled “Commemorating Missouri’s Constitution.”
That Missouri perspective is important.
Every state operates under its own constitution within the federal constitutional system. Missouri’s Constitution establishes the fundamental structure of state government, distributes governmental authority, contains Missouri’s Bill of Rights and establishes rules affecting elections, courts, taxation, education, local government and other functions of state government.
Missouri also has a considerably different constitutional history from the federal government.
While the United States continues to operate under the Constitution drafted in 1787 and subsequently amended, Missouri has adopted four constitutions — in 1820, 1865, 1875 and 1945.
The Missouri State Archives confirms those four adopted constitutions. The fourth, approved by voters in 1945 and amended numerous times since, remains Missouri’s Constitution today.
Missouri Constitution – Missouri has its own Constitution
The U.S. Constitution establishes the federal governmental system. The Missouri Constitution establishes Missouri’s state governmental system within that federal framework.
Missouri’s Constitution is not merely a historical document.
It determines how state government is organized and how governmental power is distributed. Missouri legislators, governors, judges, and other public officials exercise authority within the constitutional system the people of Missouri established.
The Constitution also establishes rights and limitations on governmental authority.
The current document begins:
“We, the people of Missouri…”
The preamble states that the people establish the Constitution “for the better government of the state.”
Article I is expressly titled “Bill of Rights.” Its provisions address the source of political power, natural rights, equality under the law, religious freedom and numerous other rights and governmental limitations.
That makes Missouri’s Constitution relevant to far more than lawyers and elected officials.
Missouri residents vote on constitutional amendments. State courts interpret constitutional provisions. The General Assembly operates within constitutional limits, and state and local government actions can raise questions under the state Constitution.
The Constitution is therefore active law.
Missouri Constitution – Four constitutions emerged from six conventions
Missouri Constitution: An important distinction in Missouri history involves the difference between a constitutional convention and an adopted constitution.
Missouri has held six major constitutional conventions:
- 1820
- 1845–46
- 1865
- 1875
- 1922–23
- 1943–44
Only four resulted in constitutions that were ultimately adopted: 1820, 1865, 1875, and 1945. Missouri State Archives records document all six convention periods.
The 1845–46 convention produced a proposed constitution that voters rejected.
The 1922–23 convention took a different approach, proposing 21 amendments rather than an entirely new constitution. Missouri voters considered those proposals at a special election in 1924, but none ultimately became part of the Constitution.
That distinction matters.
Missouri has held six constitutional conventions but adopted only four constitutions.
Missouri Constitution – Missouri’s first Constitution was written in St. Louis
Missouri’s constitutional history begins in St. Louis.
Missouri was still a territory when Congress authorized residents to establish a constitution and state government as part of the process leading toward statehood.
The issue became entangled with the country’s growing political conflict over slavery.
The Missouri Compromise permitted Missouri to move toward admission as a slave state while Maine entered as a free state, maintaining the existing balance between free and slave states in Congress. Congress passed Missouri’s Enabling Act on March 6, 1820.
Missouri’s first constitutional convention subsequently met at the Mansion House Hotel in St. Louis.
Delegates worked quickly.
According to the Missouri State Archives, delegates wrote the first Missouri Constitution in only 38 days and adopted it on July 19, 1820.
That was more than a year before Missouri formally entered the Union.
Missouri held its first state election on August 28, 1820, when Alexander McNair was elected the state’s first governor.
The first Missouri General Assembly began its session on September 18, 1820, at the Missouri Hotel in St. Louis.
Missouri formally became the 24th state on August 10, 1821.
For St. Louis residents, that history provides an important local connection to Missouri constitutional government: the state’s original Constitution was drafted in St. Louis.
The first Missouri Constitution reflected a slave state
Missouri’s first Constitution also reflected the political and social conditions surrounding its admission to the Union.
Missouri entered as a slave state following one of the young nation’s major political confrontations over the expansion of slavery.
Its early constitutional system included provisions and restrictions that reflected the period’s racial discrimination.
That history matters when examining Missouri’s constitutional development.
Constitutions can establish rights and restrict government power, but they can also reflect injustices and political attitudes prevalent when they were written.
Missouri’s subsequent constitutions provide additional examples of that reality.
Missouri Constitution – Missouri’s second convention failed
By the 1840s, Missouri’s population and economy had changed substantially.
The state convened another constitutional convention.
The second Missouri Constitutional Convention began meeting in Jefferson City on November 17, 1845. Delegates proposed changes involving subjects including judicial terms and representation in the Missouri House and Senate.
They produced a proposed replacement for the 1820 Constitution.
Missouri voters rejected it in August 1846.
The Missouri State Archives says restrictive anti-banking and anti-corporation proposals conflicted with the state’s changing economic environment and contributed to the proposed Constitution’s overwhelming rejection.
Missouri therefore continued operating under its 1820 Constitution.
The episode illustrates an enduring principle of Missouri constitutional government:
A convention can propose a constitution, but the people determine whether that document becomes the state’s fundamental law.
The Civil War transformed Missouri’s Constitution
Missouri’s next constitutional transformation came during the Civil War.
Missouri remained in the Union, but residents were deeply divided between Union and Confederate sympathies.
Delegates assembled in St. Louis on January 6, 1865, for Missouri’s third constitutional convention.
Before completing a new Constitution, delegates took one of the most consequential actions in state history.
On January 11, 1865, the convention approved an ordinance abolishing slavery in Missouri.
Only four delegates voted against it, according to the Missouri State Archives.
The timing was significant.
Missouri acted three weeks before Congress proposed the 13th Amendment to the U.S. Constitution. The federal amendment did not take effect until December 1865.
An important distinction should be made when recounting this history:
The convention abolished slavery through a separate ordinance.
Slavery in Missouri was therefore abolished by that convention action rather than simply through the later ratification of the new state Constitution.
Missouri Constitution – The Drake Constitution imposed loyalty restrictions
The 1865 convention produced the new Constitution, known as the Drake Constitution after Charles D. Drake, an influential figure in the convention.
The document reflected the bitter political divisions created by the Civil War.
Its loyalty provisions included what became known as the Ironclad Oath, which required people in numerous professions to swear that they had not aided the Confederacy.
Missouri State Archives material says professionals including teachers, physicians, attorneys, military personnel and elected officials were among those affected, and people who would not take the oath could not work in their professions.
Missouri voters ratified the 1865 Constitution.
The loyalty requirements soon generated constitutional challenges, including the U.S. Supreme Court’s 1867 decision in Cummings v. Missouri.
The controversy provides a useful example of the relationship between state and federal constitutional authority.
Missouri has its own Constitution, but state law and the state Constitution remain subject to the U.S. Constitution.
The 1865 document did not last long.
Missouri’s third Constitution arrived in 1875
Political conditions changed substantially during the decade following the Civil War.
Missouri held its fourth constitutional convention in 1875.
The resulting document became Missouri’s third adopted Constitution on October 30, 1875.
Unlike its immediate predecessor, the 1875 Constitution proved durable.
It remained Missouri’s governing Constitution for approximately 70 years.
The document addressed government organization, taxation, education, and numerous other subjects. It also reflected the period’s considerable distrust of governmental and legislative power.
But the Constitution also contained provisions reflecting racial discrimination.
Missouri State Archives records state that the 1875 Constitution mandated separate schools.
Missouri’s constitutional history therefore includes both efforts to structure and restrain government and constitutional provisions that institutionalized unequal treatment.
Missouri Constitution – Missouri tried constitutional reform again in the 1920s
By the early 20th century, Missouri again confronted demands for constitutional reform.
The state’s fifth constitutional convention began in 1922 and continued into 1923.
Rather than submitting an entirely new constitution to Missouri voters, the convention ultimately proposed 21 constitutional amendments.
Missouri voters considered the convention’s proposals at a special election on February 26, 1924, but none ultimately became part of the Constitution.
The distinction is important because the 1922–23 convention did not produce Missouri’s fourth Constitution.
The state continued operating under the 1875 document.
Another two decades would pass before Missouri voters approved an entirely new constitution.
Missouri Constitution – Missouri’s sixth convention produced today’s Constitution
Missouri’s sixth constitutional convention convened in Jefferson City on September 21, 1943, while the United States was fighting World War II.
Delegates spent more than a year developing a replacement for the 1875 Constitution.
Their work ultimately produced the document submitted to Missouri voters in early 1945.
Voters approved Missouri’s fourth Constitution on February 27, 1945. Missouri State Archives records identify it as the state’s fourth approved constitution.
The new Constitution took effect on March 30, 1945.
That distinction is important.
Missouri voters approved the Constitution on February 27.
March 30 was when it took effect.
The Missouri State Archives says the new document restructured aspects of state government administration, tax collection and provisions relating to local government.
It remains Missouri’s Constitution today, although voters have amended it repeatedly.
Missouri Constitution – The 1945 Constitution also reflected its time
The 1945 Constitution modernized important aspects of Missouri government, but its history also includes a fact that should not be overlooked.
Missouri State Archives records say delegates to the 1943–44 constitutional convention opted to continue the practice of segregated schools in Missouri.
That provides another example of why constitutional history should be examined rather than merely celebrated.
Missouri’s successive constitutions reflected the political and social conditions of their periods. Some provisions expanded or reorganized government. Others preserved practices later recognized as discriminatory or unconstitutional.
Understanding both sides of that history provides a clearer picture of Missouri’s constitutional development.
Missouri Constitution – Missouri has its own Bill of Rights
Missouri’s current Constitution does considerably more than organize state government.
It contains a state Bill of Rights in Article I.
This differs structurally from the U.S. Constitution, where the federal Bill of Rights consists of the first 10 amendments adopted after the original document.
Missouri’s Bill of Rights is incorporated directly into the Constitution’s first article.
Article I addresses the source of political power, natural rights, equality under the law, religious freedom and other individual rights and limitations on government.
That means Missourians can encounter constitutional protections under both the Missouri and U.S. constitutions.
Depending on the issue, a legal dispute may involve one document or both.
State constitutions therefore should not be viewed simply as smaller copies of the federal Constitution. They are independent sources of state constitutional law operating within the federal constitutional system.
Missouri Constitution – Political power begins with the people
One of the most important principles appears at the beginning of Missouri’s Bill of Rights.
Article I identifies the people as the source of political power.
That principle has practical consequences.
Missouri voters exercise direct authority to change their Constitution.
The Missouri State Archives states that every proposed constitution or constitutional amendment must be put to a vote of the people.
Missouri history demonstrates that authority repeatedly.
Voters rejected the proposed Constitution following the 1845–46 convention.
They approved the constitutions of 1865, 1875 and 1945.
The proposals produced by the 1922–23 convention did not become part of the Constitution.
Missouri voters still decide proposed constitutional amendments today.
Missouri Constitution – Constitutional amendments are different from statutes
The distinction between an ordinary law and a constitutional amendment matters for voters.
An ordinary statute becomes part of Missouri statutory law and can generally be changed later through the legislative process, subject to constitutional requirements.
A constitutional amendment becomes part of Missouri’s fundamental governing law.
Changing a constitutional provision generally requires another constitutionally authorized amendment.
When Missourians vote on a constitutional amendment, therefore, they are doing more than deciding an ordinary policy question.
They are participating directly in the continuing authorship of Missouri’s fundamental law.
Missouri voters periodically face an even larger constitutional question.
Article XII of the Missouri Constitution provides for submitting the question of whether to hold a constitutional convention to voters at specified intervals. Missouri voters most recently considered such a question in 2022. The official ballot language explained that if a convention were called, any revisions or amendments it produced would subsequently be submitted to the people for consideration.
Missouri Constitution – Missouri’s Constitution divides governmental power
Like the federal Constitution, Missouri’s constitutional system separates governmental authority among legislative, executive and judicial branches.
The legislative branch is the Missouri General Assembly, consisting of the House of Representatives and Senate.
The executive branch is headed by the governor and includes other statewide offices.
The judicial branch includes Missouri’s courts, headed by the Supreme Court of Missouri.
This separation is meant to prevent governmental power from being concentrated in one institution.
But Missouri’s constitutional structure also includes institutions and procedures shaped by the state’s own political history.
One prominent example is the way certain Missouri judges are selected.
Missouri Constitution – The Missouri Plan became nationally influential
Missouri voters adopted the Nonpartisan Selection of Judges Court Plan, commonly known as the Missouri Plan, through a 1940 constitutional amendment.
The system uses nonpartisan judicial commissions to select judges covered by the plan. Judges subsequently face voters in retention elections rather than running against opposing candidates in conventional partisan contests.
The Missouri Plan survived the transition from the 1875 Constitution to the 1945 Constitution and remains an important part of the state’s constitutional system.
It also became influential beyond Missouri as other jurisdictions considered methods of judicial selection intended to reduce partisan political influence.
For Missouri voters, judicial retention elections are another example of constitutional government operating in ordinary civic life.
Missouri Constitution – Four constitutions tell Missouri’s story
Missouri’s four adopted constitutions can be viewed as milestones in the state’s political history.
The 1820 Constitution accompanied Missouri’s transition from territory to statehood and reflected the national conflict over slavery.
The 1865 Constitution emerged during the final months of the Civil War, shortly after the convention separately abolished slavery in Missouri, and reflected bitter disputes over loyalty and political participation.
The 1875 Constitution reflected post-Civil War Missouri and governed the state through enormous economic and social change while also maintaining racial segregation in public education.
The 1945 Constitution reorganized important elements of state government and remains the foundation of Missouri government today.
But the unsuccessful constitutional efforts are part of that history, too.
The proposed 1845–46 Constitution was rejected.
The amendments produced by the 1922–23 convention did not become part of the Constitution.
Those outcomes reinforce one of the central themes of Missouri constitutional government:
The people ultimately decide.
Missouri Constitution – Why September 17 matters to Missouri
September 17 commemorates the signing of the U.S. Constitution on September 17, 1787.
It is not the anniversary of the signing, ratification, or effective date of Missouri’s current Constitution.
Missouri voters approved the current state Constitution on February 27, 1945, and it became effective March 30.
But Constitution Day provides an appropriate opportunity to examine both levels of constitutional government.
The Missouri Press Association has encouraged that approach through educational materials that focus attention on Missouri’s own Constitution.
For Missourians, the distinction is useful.
The federal Constitution establishes the national governmental framework and limits what states may do.
The Missouri Constitution establishes Missouri’s governmental framework within that federal system.
Missourians live under both.
Missouri’s Constitution continues to change
Missouri constitutional history did not end in 1945.
The Constitution has been amended repeatedly since it became effective.
The Missouri State Archives describes the 1945 Constitution as the state’s adopted Constitution “still in effect with amendments.”
Missouri voters therefore continue writing the state’s constitutional history.
When voters approve an amendment, its provisions become part of Missouri’s fundamental governing law.
That makes the Missouri Constitution considerably more than a document describing how government operated eight decades ago.
It remains a living part of contemporary elections, government and law.
Missouri Constitution – Constitution Day offers a reason to read it
One of the simplest ways Missourians can observe Constitution Day on September 17, 2026, is to read their state Constitution.
The Missouri Secretary of State publishes the complete Constitution under state law and makes it available to the public at no charge.
Read the Missouri Constitution from the Missouri Secretary of State – PDF.
Readers may be surprised by how many subjects encountered in elections and public-policy debates have constitutional foundations.
The document addresses individual rights, governmental powers, elections, courts, taxation, education, local government and numerous other subjects.
Understanding those provisions can make constitutional amendments appearing on Missouri ballots easier to evaluate and state government easier to understand.
September 17 begins with an event in Philadelphia that occurred nearly 240 years ago.
But Missouri has its own constitutional story.
It began at the Mansion House Hotel in St. Louis in 1820, before Missouri officially became a state.
It continued through slavery and the Civil War, emancipation, Reconstruction, segregation, political reform and the governmental changes of the 20th century.
Missouri held six major constitutional conventions.
Four constitutions were adopted.
The fourth became effective on March 30, 1945, and remains Missouri’s fundamental governing document today.
Most importantly, Missouri’s constitutional history demonstrates that the Constitution does not belong exclusively to governors, legislators, judges or lawyers.
Its authority ultimately comes from the people.
Missouri voters approved it.
Missouri voters have amended it.
And Missouri voters will continue deciding whether it should change.
That gives Constitution Day on September 17 a particularly useful purpose for Missouri residents: commemorating the nation’s founding document while taking the opportunity to understand their own Constitution and the government it creates.
