231 years ago today, on January 13, 1794 (December 12, 1793 in the lunar calendar), the U.S. Congress passed a bill on the flag. According to records, in the early days of the Revolutionary War, on June 14, 1777, the Second Continental Congress officially confirmed: "The American flag has 13 stripes in red and white, and the upper left corner of the flag should be blue with 13 stars on it." However, it did not mention that there should be more red and white, how the positions of the stars should be arranged, and how many angles should the stars be. Therefore, from 1777 to 1795, there were many styles of flags. Some even violate meeting decisions, such as using red and blue stripes or red, white and blue stripes. As for the shapes of stars, there are pentagonal, hexagonal, heptagonal and even octagonal. Vermont and Kentucky joined the U.S. Federation in 1791 and 1792. On January 13, 1794, Congress passed a resolution to add two flags and two stripes to the national flag to represent these two states, and stipulated that there should be one more red and white stripes, and the star in the upper left corner should be pentagonal. American national anthem author Francis Scott Key saw the flag during the War of 1812, which inspired him to write the song "The Stars and Spangled Banner Never Set" in 1818. From then on, the American flag was called the "Stars and Stripes". Later, more and more states joined the union, and these new states required the addition of stars and stripes to represent them on the flag. In order to ensure the proportion of the flag, Congress decided in 1818 to restore the stripes to the original 13 lines and stipulated that newly added states would only add one new star to the flag, but not more stripes.