Which document outlined the first form of government for the United States? Which system of government did this document create?

In 1787, the delegates of the convention created a plan to create America; s national government. The plan was to create a document that contained all the fundamental laws and ensured basic human rights for every citizen of America, this document is known as the constitution. The constitution established the nation government in America. The government has three branches; executive, legislative and judicial. There is also a system in place that ensures that none of the three branches will ever become overpowered.