The United States Air Force (USAF) was officially founded as an independent military branch on September 18, 1947 it first appeared as the U.S. Army Signal Corps' Aeronautical Division in 1907, then the Army Air Service, Army Air Corps, and Army Air Forces during World War II
The United States Navy was officially established on October 13, 1775 on May 8, 1911: The U.S. Navy purchased its first aircraft (this date is often considered the birth of U.S. Naval Aviation.) and their first carrier commissioned March 20, 1922 (CV-1 USS Langley)
The United States Marine Corps (USMC) was founded on November 10, 1775, by the Second Continental Congress to raise two battalions of Continental Marines to support naval operations during the American Revolutionary War.
The Continental Army was established June 14, 1775 this date is celebrated as the birthday of the U.S. Army. however on November 2, 1783 the main Continental Army was disbanded,. On June 3, 1784 The United States Army, as a standing force, was officially created although it did not use that name till 1796.
August 4, 1790: The Revenue Cutter Service was established by Congress. This date is considered the USCG's official birthday January 28, 1915 The United States Revenue Cutter Service merged with the U.S. Life-Saving Service to officially form the United States Coast Guard.