Which of the following significant events occurred in 1777?

The adoption of the American Flag in 1777 was a significant event in American history as it symbolized the unity of the thirteen colonies and their struggle for independence. The design of the flag reflected the colonies' desire for independence from British rule, with the stars representing the states and the stripes signifying the original colonies. This event marked a pivotal moment, as the flag became an enduring symbol of American identity and patriotism.

The other events mentioned have different historical contexts. The Constitution was approved later, in 1787. The Declaration of Independence was published in 1776, which is critical to understanding the timeline of American independence. The Treaty of Paris, which formally ended the Revolutionary War, was signed in 1783. Thus, the adoption of the American Flag is distinctly significant to the timeline of the patriotic symbols that emerged during the revolution.