After the colonies declared their independence from the crown they joined together to form one country, however each state was self governing.
In order prevent infighting and animosity between them it was sought to create a single unified government. With that in mind, every state sent a delegate to meet in a convention to plan how this was to be done, the result of this convention was the creation of the first government in the United States in 1781 under the "The Articles of the Confederation".
This new central government proved to be weak and ineffective and failed to prevent infighting between states over land boundaries and taxes.
As such it was sought to create a stronger federal government to overcome the deficiencies the first government had.
After many meetings and discussions, on September 17th 1787, during the Philadelphia Constitutional Convention, the United States Constitution was finally signed.
