2024
First observance
National Bunion Day
Treace announced April 16, 2024 as the first-ever National Bunion Day in the United States.
Evergreen date guide
What is celebrated on April 16?
See the observances and verified observance-history milestones attached to April 16. 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.
2010
First observance
Foursquare Day (4SQDay)
Contemporaneous Tampa reporting identifies April 16, 2010 as the first Foursquare Day launch.
2008
First observance
National Healthcare Decisions Day
The organizer states NHDD was founded in 2008 as an annual April 16 initiative.
Reviewed depth
Other in-depth guides on April 16
Source-backedFixed AnnualIn-depth guide
Foursquare Day (4SQDay)
Foursquare’s own material describes 4SQDay as an annual community holiday centered on April 16, with community events sometimes scheduled around that date.
Source-backedFixed AnnualIn-depth guide
International Documentary Day
Organizer-side launch material describes April 16 as an annual documentary observance beginning in 2026, and current calendar coverage likewise specifies April 16 every year.
Source-backedFixed AnnualIn-depth guide
José de Diego Commemoration Day
Puerto Rico law preserves April 16 as a commemorative day for José de Diego while distinguishing it from the consolidated Próceres public holiday.
Source-backedFixed AnnualIn-depth guide
National Bean Counter Day
National Day Calendar credits Connecticut CPA Kevin Wenig with founding National Bean Counter Day on April 16; Hartford Business Journal independently identified Wenig as the local accounta…
Source-backedFixed AnnualIn-depth guide
National Healthcare Decisions Day
The Conversation Project states that National Healthcare Decisions Day is an annual April 16 initiative founded in 2008 by attorney Nathan Kottkamp to encourage advance-care-planning conver…
Source-backedRule Based AnnualIn-depth guide
National High Five Day
Official project material verifies a 2002 University of Virginia student origin and third-Thursday-in-April recurrence.
Explore the mix
All topics →Topics represented on April 16
7 observances
All observances on this date
Source-backedFixed AnnualIn-depth guide
Foursquare Day (4SQDay)
Foursquare’s own material describes 4SQDay as an annual community holiday centered on April 16, with community events sometimes scheduled around that date.
Source-backedFixed AnnualIn-depth guide
International Documentary Day
Organizer-side launch material describes April 16 as an annual documentary observance beginning in 2026, and current calendar coverage likewise specifies April 16 every year.
Source-backedFixed AnnualIn-depth guide
José de Diego Commemoration Day
Puerto Rico law preserves April 16 as a commemorative day for José de Diego while distinguishing it from the consolidated Próceres public holiday.
Source-backedFixed AnnualIn-depth guide
National Bean Counter Day
National Day Calendar credits Connecticut CPA Kevin Wenig with founding National Bean Counter Day on April 16; Hartford Business Journal independently identified Wenig as the local accounta…
Source-backedFixed AnnualIn-depth guide
National Healthcare Decisions Day
The Conversation Project states that National Healthcare Decisions Day is an annual April 16 initiative founded in 2008 by attorney Nathan Kottkamp to encourage advance-care-planning conver…
Source-backedRule Based AnnualIn-depth guide
National High Five Day
Official project material verifies a 2002 University of Virginia student origin and third-Thursday-in-April recurrence.
Source-backedFixed AnnualIn-depth guide
World Voice Day
World Voice Day Committee and international voice-health community
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 →