In 1781 the Articles of Confederation were signed as the first US government. It gave most power to the states with only a weak central government.
The Articles of Confederation
However, the federal government was too weak to function, and had trouble resolving disputes between states
In 1787 there was Constitutional Convention held to make a new constitution for the US as the Articles did not work. The new US Constitution gave more power to the federal government so that the country can function unitedly and efficiently