U.S. Constitution, Article VII
Ratification
The Ratification of the Conventions of nine States, shall be sufficient for the Establishment of this Constitution between the States so ratifying the Same.
Notes
Sets ratification by conventions of nine states as sufficient for establishing the Constitution between the states that ratify it. The Constitution takes effect only among the ratifying states once nine have approved it, and ratification is by state conventions rather than by state legislatures.
Use as reference
Lexinter.net | U.S. Const. art. VII | https://laws.lexinter.net/constitution/us/article-7