What does the rectangle on the US flag mean?

Key decisions of the Supreme Court under the leadership of John Marshall solidified the power of the Supreme Court to? Who were the Commanders of the Union Army? Where did kids in the colonial times go to the bathroom in school? Name two things DrKing did to make America away of the discrimination of African Americans? How much is a mint condition 1864 Confederate bond worth? What was the state of civilization in Africa and the Americas around 1050? How did abolitionists try to end slavery? Is Dana falkenberg alive? When did they pass the 15th amendment? Who was the richest man in New England at the time of the revolutionary war? What is the value of a 1857 wheat penny? How many crimes are there in one day? What was Lincoln's initial stance when the south began to secede? Who was the leading spokesman of African Americans during the civil war? How did Native Americans respond to restrictions placed upon them by the US government? Why is September 11 2001 significant? Which of the following industries grew esplosively during the 1920s? What did the tunica Indians hunt and eat? What could you buy with a silver half dollar in 1918? Who was the commander in chief at the opening of the US Civil War?