Below are four different designs from the history of the United States. There have been 27 different flag designs since 1776 — all slight variants on the stars and stripes theme, retooled to reflect the current number of states. (The 13 stripes remain the same to represent the original thirteen colonies.) Starting with the fourth version of the flag, which began service in 1818, every flag change started on July 4 of the year following any new admissions to the union. In legalese: “WHEREAS section 2 of title 4 of the United States Code provides as follows: ‘On the admission of a new State into the Union one star shall be added to the union of the flag; and such addition shall take effect on the fourth day of July then next succeeding such admission.'”
Original 13-star flag
Here’s the original USA flag, with 13 stars representing the states of Delaware, Pennsylvania, New Jersey, Georgia, Connecticut, Massachusetts, Maryland, South Carolina, New Hampshire, Virginia, New York, North Carolina and Rhode Island. It flew from June 14, 1776 until May 1, 1795.
This flag with fifteen stars flew from May 1, 1795 through July 3, 1818, and came into service when Vermont and Kentucky became American states.
Here, an unidentified boy holds a 34-star US flag, which means this ambrotype photo was taken sometime between July 4, 1861 and July 3, 1863.