When is Air Force Birthday in United States?

September 2, Labor Day September 4, World Sexual Health Day September 5, International Day of Charity September 7, Carl Garner Federal Lands Cleanup Day September 8, National Grandparents Day September 8, International Literacy Day September 9, California Admission Day September 10, World Suicide Prevention Day September 11, Patriot Day September 12, International Day for South-South Cooperation September 12, International Programmers' Day September 13, Friday the 13th September 15, International Day of Democracy September 16, The Prophet's Birthday September 16, International Day for the Preservation of the Ozone Layer September 17, Constitution Day and Citizenship Day September 18, Air Force Birthday September 20, National POW/MIA Recognition Day September 21, International Day of Peace September 22, September Equinox September 22, Emancipation Day September 23, International Celebrate Bisexuality Day September 26, World Maritime Day September 26, International Day for the Total Elimination of Nuclear Weapons September 27, Native American Day September 27, World Tourism Day September 28, World Rabies Day September 29, World Heart Day September 29, Gold Star Mother's Day