The First United States Congress proposed twelve amendments in 1789, before the America250 era.
Congress approved the proposals on September 25, 1789, after James Madison introduced a package of constitutional amendments. The proposals were intended partly to answer concerns raised during state ratification debates and to protect individual liberties.
The states ratified ten of the twelve proposals by December 15, 1791. Those ten became the Bill of Rights. The first proposal, concerning the size of congressional districts, was not ratified at the time, while the second proposal concerning congressional pay was eventually ratified in 1992 as the Twenty-seventh Amendment.
Because of this history, the Bill of Rights contains ten amendments even though Congress originally sent twelve to the states. The numbering of the surviving amendments was adjusted after the first two proposals failed to gain immediate approval.