The purpose of the passage is to ______.

The history of American flag goes back to the thirteen British colonies that became the first American states. Each colony had its own flag. But, during the Revolutionary War against Britain, all the colonies fought together under a common flag. It had red and white stripes, thirteen in all, one for each colony. And it had a blue square in the upper left corner. Red was for honor, white for innocence and blue for justice. Inside the blue square were the red cress and white stripes of the Test Five British flag.
   The American colonists declared their independence on July fourth, seventeen seventy-six. Then, on June fourteenth, seventeen seventy-seven, the Continental Congress approved the design of a national flag. Thirteen red and white stripes remained. But now thirteen white stars replaced the British Union Jack inside the blue area. The stars were meant to represent "a new constellation."
   Two more stripes were added when two more states joined the Union after the Revolutionary War.
   In eighteen seventeen, Congress passed a law to require that the flag return to thirteen stripes, to honor the first colonies. But the number of stars increased as new states joined the Union. Today there arc fifty states, and fifty stars.
   A delegate to the Continental Congress, Francis Hopkinson, took credit for the flag design. And tradition says a committee led by George Washington asked a woman with expert sewing skills, Betsy Ross, to make the first flag. Betsy Ross lived in Philadelphia, Pennsylvania.