What is a constitutional amendment?

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A constitutional amendment alters the Constitution of the United States by striking or inserting new language. The Constitution establishes the structure, powers and responsibilities of the federal government.

27

The number of times the Constitution has been amended.

1992

The last time the Constitution was amended.

Delegates at the Constitutional Convention created the Constitution in response to growing limitations of the Articles of Confederation. The articles, adopted on November 15, 1777, served as the country’s first constitution, but they did not establish enforcement powers, commerce regulation or the ability to print money. As a result, Congress called state delegates to a Grand Convention, as it was then known, to revise the articles.


The convention assembled in May 1787, and by mid-June, delegates had decided to rework the entire structure of the government. By September, the framers called for conventions in each state to ratify the Constitution. Nine of the 13 states in the Union would need to approve it.


Delaware was the first state to ratify it, doing so on December 7, 1787. New Hampshire became the deciding ninth state on June 21, 1788.

The constitutional amendment process is as follows:

Step 1

Two-thirds vote

An amendment may be proposed by a two-thirds vote in both the House of Representatives and the Senate or by a constitutional convention called by two-thirds of state legislatures.

Step 2

Three-fourths ratification

Once proposed, the archivist of the United States submits the amendment to the states for consideration. It becomes part of the Constitution once it is ratified by three-fourths of the states.

When was each amendment ratified?


The United States has added 27 amendments since the Constitution’s enactment in 1789. The first 10 were ratified at once on December 15, 1791, and are now known as the Bill of Rights. The 27th Amendment on May 7, 1992, was the most recent change.

Amendment ratifications come in clusters, not a steady trickle.

Timeline of constitutional amendments’ ratification, 1791-1992

How many days did it take to ratify each amendment?


The 26th Amendment, which set the national voting age to 18, took the shortest amount of time to ratify: 100 days from the date it was proposed by Congress to the date it was ratified by the required number of states. The 27th Amendment, which addressed congressional compensation, took the longest: 74,003 days, or nearly 203 years. Of the 27 ratified amendments, the average time to ratification was 617 days.

On average, amendments took 617 days to be ratified.

Years from proposal to ratification, by amendment (excluding the 27th Amendment)

Note: The 27th Amendment, which addresses congressional compensation, is excluded from this chart. Its 74,003-day ratification period, between 1787 and 1992, is roughly 50 times longer than the next-longest amendment and would compress the remaining bars beyond readability.

Browse all 27 amendments

Browse all 27 amendments

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Methodology

USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.

Page sources

USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.