A score is equal to 20 years. Four

score and seven years ago is how the

speech began. Why did Lincoln refer to

that year?

That was when the Declaration of Independence was sighned.

Lincoln's address starts with "Four score and seven years ago." A score is equal to 20 years, so he was referencing 87 years ago - 1776, when the Declaration of Independence was signed. The speech was made, then, seven score and seven years ago.