2021
First observance
National Cartonnage Day
Colorway Arts announced and held the first documented National Cartonnage Day event on September 18, 2021.
Evergreen date guide
What is celebrated on September 18?
See the observances and verified observance-history milestones attached to September 18. Each observance keeps its own source and date details.
Verified history
Today in history →On this date in observance history
Selected observance milestones connected to this date, based on reviewed sources.
2020
First observance
International Equal Pay Day
UN Secretary-General and UN system material identify 18 September 2020 as the first International Equal Pay Day.
2014
First observance
Read an Ebook Day
OverDrive’s 2014 launch explicitly calls September 18 the first International Read an eBook Day.
2009
First observance
World Bamboo Day
WBO organizational history states that the first World Bamboo Day was celebrated on September 18 at the 2009 Bangkok congress.
2008
Later action
National Good Neighbor Day
Recognized the importance of National Good Neighbor Day and described an annual fourth-Sunday-in-September tradition without creating a permanent federal public holiday.
2008
First observance
National HIV/AIDS and Aging Awareness Day
NIH states that the observance was launched on September 18, 2008.
2008
Later action
National Neighbor Day
Recognized the importance of National Neighbor Day and called on people and organizations to celebrate its goals in 2008.
2000
Institutional decision
Philippine-British Friendship Day
Proclamation No. 381 is dated September 18, 2000.
Reviewed depth
Other in-depth guides on September 18
Source-backedFixed AnnualIn-depth guide
Chile Independence Day
Chile’s Biblioteca del Congreso Nacional verifies Law No. 2,977 listing September 18 as a holiday commemorating national independence and explains that the date reflects the First Governmen…
Source-backedFixed AnnualIn-depth guide
International Equal Pay Day
A/RES/74/142
Source-backedRule Based AnnualIn-depth guide
International Grenache Day
Grenache Association first-party history says International Grenache Day was launched in 2010 after the first International Grenache Symposium and is now held annually on the third Friday o…
Source-backedRule Based AnnualIn-depth guide
National Concussion Awareness Day®
The official National Concussion Awareness Day® site states that Brooke Mills founded the observance in 2016 and that it is recognized on the third Friday of September each year. A 2018 org…
Source-backedFixed AnnualIn-depth guide
National HIV/AIDS and Aging Awareness Day
HIV.gov and NIH identify September 18 as National HIV/AIDS and Aging Awareness Day. NIH states that The AIDS Institute launched the observance on September 18, 2008; current federal materia…
Source-backedRule Based AnnualIn-depth guide
National POW/MIA Recognition Day
Public Law 95-349 designated July 18, 1979 as National P.O.W.-M.I.A. Recognition Day and President Jimmy Carter issued Proclamation 4664 for that inaugural observance. Current Defense POW/M…
Explore the mix
All topics →Topics represented on September 18
10 observances
All observances on this date
Source-backedFixed AnnualIn-depth guide
Chile Independence Day
Chile’s Biblioteca del Congreso Nacional verifies Law No. 2,977 listing September 18 as a holiday commemorating national independence and explains that the date reflects the First Governmen…
Source-backedFixed AnnualIn-depth guide
International Equal Pay Day
A/RES/74/142
Source-backedRule Based AnnualIn-depth guide
International Grenache Day
Grenache Association first-party history says International Grenache Day was launched in 2010 after the first International Grenache Symposium and is now held annually on the third Friday o…
Source-backedRule Based AnnualIn-depth guide
National Concussion Awareness Day®
The official National Concussion Awareness Day® site states that Brooke Mills founded the observance in 2016 and that it is recognized on the third Friday of September each year. A 2018 org…
Source-backedFixed AnnualIn-depth guide
National HIV/AIDS and Aging Awareness Day
HIV.gov and NIH identify September 18 as National HIV/AIDS and Aging Awareness Day. NIH states that The AIDS Institute launched the observance on September 18, 2008; current federal materia…
Source-backedRule Based AnnualIn-depth guide
National POW/MIA Recognition Day
Public Law 95-349 designated July 18, 1979 as National P.O.W.-M.I.A. Recognition Day and President Jimmy Carter issued Proclamation 4664 for that inaugural observance. Current Defense POW/M…
Source-backedFixed AnnualIn-depth guide
National Respect Day
Contemporaneous 2008 reporting identifies the first annual National RESPECT! Day on September 19, 2008 through the Family Violence Prevention Fund–Macy’s campaign; current histories record…
Source-backedFixed AnnualIn-depth guide
Read an Ebook Day
OverDrive states that Read an Ebook Day takes place every September 18 and documents the campaign’s 2014 launch.
Source-backedFixed AnnualIn-depth guide
World Bamboo Day
World Bamboo Organization first-party pages verify September 18, state that WBO created World Bamboo Day in 2009, place the first celebration at the 8th World Bamboo Congress in Bangkok, an…
Source-backedFixed AnnualIn-depth guide
World Water Monitoring Day
U.S. EPA material documents the inaugural World Water Monitoring Day in 2003 as coordinated by America’s Clean Water Foundation and the International Water Association, originally centered…
How dates are selected
This page combines fixed annual dates, reusable calendar rules and year-specific dates confirmed for 2026. Variable or historical dates are included only when they are clearly supported.
Read the methodology →