- National Physical Fitness and Sports MonthMay
- National Youth Traffic Safety MonthMay
- National Flower MonthMay
- Sudoku First Published as Number Place in Dell Puzzle MagazineMay, 1979
- Most Powerful Earthquake of the 20th Century Struck ChileMay 22, 1960
- Margaret Wise Brown’s BirthdayMay 23, 1910
- World Turtle DayMay 23, 2013
- Hurricane Preparedness WeekMay 26-Jun 1, 2013
- National Spelling Bee WeekMay 26-Jun 1, 2013
- Cellophane Tape PatentedMay 27, 1930
- Golden Gate Bridge OpenedMay 27, 1937
- Golden Gate Bridge OpensMay 27, 1937
- Memorial DayMay 27, 2013
- Sojourner Truth Gives “Ain’t I Woman?” SpeechMay 28-29, 1851
- John F. Kennedy’s BirthdayMay 29, 1917
- First Daily American Newspaper PublishedMay 30, 1783
- President Woodrow Wilson Proclaims June 14 Flag DayMay 30, 1916
- First US copryight law passedMay 31, 1790
- Walt Whitman’s BirthdayMay 31, 1819
- Mark Felt Reveals Himself as Watergate’s Deep ThroatMay 31, 2005
- Adopt-a-Shelter-Cat MonthJune
- National Rose MonthJune
- Cancer From the Sun MonthJune
- Dairy MonthJune