Constitutional Amendment Process Simulator
Article V of the US Constitution sets deliberately high bars to change it. Choose a proposal path, set how much support an amendment has in Congress and the states, and watch it move through each gate or stop where the votes run out.
Guided Experiment: Why is two-thirds of Congress so hard to reach?
A bill becomes law with a simple majority. An amendment needs two-thirds of both houses to even be proposed. Predict whether a proposal supported by a slim majority can move forward.
Write your hypothesis in the Lab Report panel, then click Next.
Article V Process
Controls
Proposal method
Stage 1: Proposal
Stage 2: Ratification
Scenario presets
Results
Stage 1: Proposal
290 votes of 290 needed
67 votes of 67 needed
Stage 2: Ratification
38 states of 38 needed
The proposal cleared the proposal stage and was then ratified by at least 38 states. It becomes part of the Constitution.
Historical context
Of roughly 11,000 amendments proposed in Congress, only about 33 passed Congress and just 27 have been ratified. The Equal Rights Amendment is a famous near-miss. It cleared Congress but fell short of the 38 states needed for ratification.
Data Table
(0 rows)| # | Scenario | House yes | Senate yes | States ratifying | Outcome |
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Reference Guide
Two Ways to Propose
An amendment can be proposed in two ways. Congress can propose one with a two-thirds vote of both the House and the Senate. That means at least 290 of 435 in the House and 67 of 100 in the Senate.
The second path has never been used. Two-thirds of the state legislatures, which is 34 of 50, can call a national convention to propose amendments. Both paths require a supermajority, not a simple majority, just to start.
The Ratification Bar
A proposal is not an amendment until the states ratify it. Three-fourths of the states must agree, which with 50 states means 38. Three-fourths of 50 is 37.5, and because you cannot have half a state, it rounds up to 38.
Ratification counts states, not population. That gives smaller states real weight and means a change must have broad support across the whole country, not just in the most populous places.
Why Amendments Are Rare
The framers wanted the Constitution to be stable, so they set the bars high on purpose. A narrow majority cannot change it. Two separate supermajorities, first in Congress and then across the states, must line up on the same idea.
The Equal Rights Amendment shows how hard this is. It passed both houses of Congress but fell short of the 38 states needed, so it did not become part of the Constitution.
Only 27 Have Passed
Roughly 11,000 amendments have been proposed in Congress over US history. About 33 of those cleared Congress, and only 27 have been ratified by enough states to take effect.
The first ten ratified together in 1791 are the Bill of Rights. A later example is the 26th Amendment, which lowered the voting age to 18 and was ratified quickly in 1971. The high bars are the reason the list stays short.
