Recorded history by calendar date
What happened on April 20?
Explore notable historical events, births, deaths, and observances connected with April 20. This page organizes a useful shortlist from recorded history so the date is easy to scan, cite, and explore further.
Looking for the weekday and calendar conversions too? View April 20, 2026 for the same month and day in the closest available year.
Events
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Births
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Deaths
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Observances
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On This Day in History
Major events, milestones, and turning points that happened on this date.
Curated highlights
The shortlist below is ordered to surface the most notable items first while keeping the page readable. When a holiday or observance is relevant, you’ll also see direct links into the related countdown pages.
Historical Events
2010
Deepwater Horizon explosion
The drilling rig exploded in the Gulf of Mexico, killing 11 workers and causing the largest marine oil spill in history.
Births
No curated birth entries are in this shortlist for this date yet.
Deaths
No curated death entries are in this shortlist for this date yet.
Observances / Holidays
No observances are highlighted in the current shortlist for this date.
Why dates can carry multiple meanings
A single month-day can connect political milestones, scientific breakthroughs, notable lives, and annual observances. That is why Whatistheday groups this archive into events, births, deaths, and observances rather than mixing everything into one long timeline.
Some observances are fixed on the same Gregorian date every year, while others move because they follow lunar, lunisolar, or rule-based calendars. For calculation details, see the methodology page.
How long ago?
Curious how many days have passed since iconic moments in history? Browse our Days Since directory — live counters for the Moon landing, the fall of the Berlin Wall, 9/11, and more.
Who was born on April 20?
See famous people born on this date — filterable by footballers, actors, musicians, scientists and more. View birthdays for April 20 →