What was the document that was created when when the united states first gained independence?

The document is called the Declaration of Independence. It's quite a famous piece, and I encourage you to learn more about it! :) 

The Declaration of Independence was the document that gained the United States written independence from Britain. It was written by the founding fathers such as Thomas Jefferson and included a few ideas of enlightenment thinkers. The Declaration is still a famous document today and marks a great symbol of independence. Hope this helps and mark as brainliest! :)