As a judicial astrologer born & raised in Philadelphia, there are some things that many astrologers do not know about the U.S. horoscopes.
First thing is that the July 4, 1776 signing of the Declaration of Independance was supposed to be signed on July 2, but Benjamin Franklin, an practicing astrologer among his many skills, and occupations -did not want the signing to take place under a Capricorn Moon. He talked with the main writer of the Declaration, Thomas Jefferson, and both delayed the signing by making themselves unavailable until the Moon had entered Aquarius.
I use the July 4, 1776 chart as the one for the American Revolution, and the subsequent war with England.
Another chart I use for the United States is 17 September 1787 - the signing of the U.S. Constitution and 4 March 1789 - when the constitution went into effect.
Set all charts for sunrise in Philadelphia, Pennsylvania. - a classical mundane method to forecast events - and progress them over significant dates in U.S. and world history.
Much of the fighting over the "correct" date, or timing of these events can be ended with casting a simple sunrise cycle series of charts, and then progressing them using Secondary Progression by Naibod.
Many of the Founding Fathers of the U.S. - including the prime individuals -had knowledge of, and/or practiced astrology - including Franklin, and Jefferson - among others. I've read many of their writings as a boy growing up in Philadelphia, and lived in the neighborhood Franklin founded to escape the summer heat of Independance Hall in downtown Philadelphia.