What founding document was written in 1787?

Why this is the answer

The Constitution was written in 1787, at the Constitutional Convention in Philadelphia, eleven years after the Declaration of Independence. The country's first framework, the Articles of Confederation, had left the national government too weak, and the leaders who met that summer decided to replace it with a new one. The Constitution took effect after the states ratified it, and George Washington became the first President in 1789. Memory hook: 1776 Declaration, 1787 Constitution.