Constitutional Amendment Processes in the 50 States

The U.S. Constitution is difficult to change and has only been amended 27 times. State constitutions, on the other hand, are much easier to modify, and state constitutional amendments are adopted on a regular basis. The current constitutions of the 50 states have been amended around 7,000 times. 

States vary in how often they amend their constitutions. The constitutions of Alabama, Louisiana, South Carolina, Texas, and California are amended more than three to four times per year, on average. At the other end of the spectrum, the Tennessee, Kentucky, Indiana, Illinois, and Vermont constitutions are amended only once every three to four years on average.  

Below is an overview of constitutional amendment processes in the 50 states. I discuss the various possible ways of amending state constitutions, including amendments that are crafted by legislatures, citizens, conventions, and commissions. I also take note of the range of ways that states structure these amendment processes. 

Legislature-Crafted Amendments 

State legislatures generate more than 80 percent of constitutional amendments that are considered and approved around the country each year.  

States vary in their requirements for legislatures to craft amendments. Some require that amendments secure the backing of a majority of legislators, whereas others require supermajority legislative support. States also differ in whether they require legislative support to be expressed in a single session or two consecutive sessions.  

The easiest route to legislative approval of amendments is to permit approval of amendments by a majority vote in a single session — a path available in 10 states. Another 25 states set a higher threshold by requiring amendments to be proposed by a supermajority legislative vote in a single session, by a three-fifths vote in 9 of these states and a two-thirds vote in 16 states. And 11 states set a different hurdle, by requiring amendments to be approved by a majority vote in two consecutive legislative sessions, though 4 of these states provide an alternative path to the two-session requirement by allowing approval of amendments by a supermajority vote in a single session. Finally, 4 states go so far as to require amendments to be approved by a supermajority vote in one or more legislative chambers and require legislative approval in consecutive sessions. 

Every state but Delaware requires legislature-crafted amendments to be approved by voters. Amendments in Delaware take effect once they are approved by a two-thirds legislative vote in consecutive sessions.  

Most states permit voters to ratify legislature-crafted amendments by a simple majority vote. But three states set a supermajority threshold — a two-thirds vote in New Hampshire, a three-fifths vote for most amendments in Florida, and a 55-percent threshold for most amendments in Colorado. Four states — Hawaii, Minnesota, Tennessee, and Wyoming require amendments to be approved by a majority of voters in the entire election; in these states, voters who abstain from voting on an amendment essentially count as no votes. Illinois combines these approaches to voter ratification, allowing amendments to be approved if they are supported either by three-fifths of voters on the amendment or by a majority of voters participating in the entire election.  

Citizen-Initiated Amendments 

Seventeen states currently provide another path for enacting amendments: via citizen-initiative processes. Until recently, Mississippi also permitted citizen-initiated amendments, but in a 2021 ruling in a case challenging the legitimacy of a recently enacted medical marijuana legalization amendment, the Mississippi Supreme Court rendered that state’s constitutional initiative process unusable until it is revised to accurately reflect the number of congressional districts from which signatures have to be collected to qualify initiated amendments for the ballot. 

These 17 states vary in their procedures for qualifying citizen-initiated amendments for the ballot. In each of these states, amendment proponents must gather an overall number of signatures in support of holding a vote on the amendment. Most of these signature-collection requirements are tied to the number of votes cast in the last gubernatorial election. Arizona and Oklahoma set the highest bar, requiring amendment supporters to collect signatures equal to 15 percent of the votes cast in the last election for governor. Other states set a range of lower thresholds. Massachusetts sets the lowest bar, requiring amendment supporters to obtain signatures equal to 3 percent of the votes cast in the last gubernatorial election. Just over half of the states also maintain a geographic-distribution requirement for signature collection, for instance by requiring signatures to be collected from 2 percent of registered voters in every state senate district, as in Colorado. 

In all but one state where the constitutional initiative process is currently available, legislators cannot play a gate-keeping role by blocking a citizen-initiated amendment from appearing on the ballot. Once supporters meet the signature requirements and other legal requirements, the amendment is placed on the ballot, without a role for the legislature in this process. But in Massachusetts, citizen-initiated amendments must secure support from one-fourth of the members of the legislature, sitting in joint session and voting in two consecutive sessions, before they can appear on the ballot.  

Once citizen-initiated amendments qualify for the ballot, they generally have to be ratified in the same fashion as legislature-referred amendments, by a simple majority of voters in most states and by a supermajority of voters in several states. But in Nevada, citizen-initiated amendments face an additional hurdle — they must be approved by a majority of voters in two consecutive elections.  

On average, citizen-initiated amendments account for fewer than 2 out of every 10 amendments adopted around the country each year. However, in several states, such as California and Colorado, citizen-initiated amendments are considered at a particularly brisk pace.   

Convention-Framed Amendments 

State constitutional conventions were once called on a regular basis, whether to frame inaugural state constitutions or replace, revise, or adopt piecemeal amendments to existing constitutions. From 1776 to 1986, a total of 250 constitutional conventions were held in the 50 states. However, it has been nearly four decades since Rhode Island voters approved an automatically generated referendum that led to the last full-scale state constitutional convention in the United States. Rhode Island’s 1986 convention submitted 14 amendments to voters, who approved 8 of them. 

Despite the lack of convention activity in recent decades, conventions continue to offer a potential path for amending state constitutions. Generally, conventions are called by legislators, who are required to approve a convention referendum, with a majority legislative vote needed to call a convention referendum in most states and a supermajority legislative vote needed in other states. In all but a few states, a referendum on calling a convention must then be submitted to and approved by a majority of voters (some states do not require voter approval of a legislature-generated convention call). However, in four states, it is possible to bypass the legislature and call a convention through the initiative process. Additionally, in 14 states, referendums on calling a convention are required to appear on the ballot automatically at periodic intervals ranging from 10 to 20 years depending on the state.   

Although not all constitutions provide clear guidance on the rules for calling and holding conventions and approving their work, it has been long understood that conventions will submit any proposed amendments to voters for approval. In prior eras, some conventions did not submit their work for voter ratification, especially at the turn of the 20th century when some Southern disenfranchisement conventions simply proclaimed that certain changes would take effect. However, for the better part of the last century, conventions have submitted proposed amendments or revisions to voters for their approval. In general, and with some exceptions, convention-referred amendments are ratified in the same fashion as legislature-referred amendments, usually by a simple majority of voters.  

Commission-Referred Amendments 

Florida is unique in allowing constitutional commissions to submit amendments directly to voters. In a number of other states, commissions have been formed for the purpose of recommending amendments for the consideration of the legislature. But Florida is the only state where commissions are empowered to place amendments directly on the ballot. 

Florida’s constitution authorizes two separate commissions to place amendments on the ballot for voter approval. A Constitution Revision Commission meets every 20 years and can propose constitutional amendments on any subject. A separate Taxation and Budget Reform Commission also meet every 20 years, on a staggered time frame from the other commission, so that one of these commissions holds a meeting every 10 years. The latter commission can only propose amendments dealing with tax and budget items.  

The most recent meeting of one of these Florida commissions took place in 2017–18, when the Constitution Revision Commission placed a number of amendments on the 2018 ballot. Voters approved each of the seven amendments that remained on the ballot by Election Day, all by the requisite three-fifths popular vote required to approve most Florida amendments.  

John Dinan is a professor of politics and international affairs at Wake Forest University. He writes an annual review of state constitutional developments for the Book of the States.