This country could have many "Independence Days".
Of course the most popular is July 4, which is the date the Declaration was ratified
. But we could also use July 2, which is the date it was approved by the Continental Congress, or August 2, when most of the delegates actually signed it.
But there's also the Constitution. For our first decade or so, we operated under the "Articles of Confederation
", which weren't the most efficient way of doing things. A Constitutional Convention took place in 1787, which in turn led to the final draft being approved on September 17 of that year. On June 21, 1788, New Hampshire ratified the document and it became official.
But we didn't start the new government until March 4, 1789 - the first session of Congress under the new rules.