Gettysburg address what happened 87 years ago? what did it represent?

On November 19, 1863, President Lincoln gave his famous speech Gettysburg Address.

He started with "Four score and seven years ago..." (score=20 years) referencing the event happened 87 years ago. Is was a year 1776, the year when the Declaration of Independence was signed.

The Declaration of Independence represents an important part of the American history because it reflects the democratic basis of the country, ideals and goals of the nation. Also, it contains complains of the colonies against the British king. It was signed by the members of the Continental Congress on July 4 of 1776.

i think ethier way not sure