The US Holidays calendar is incomplete. Here are the annual holidays that are missing:

Valentine's Day (February 14)
President's Day (Federal - 3rd Monday of February)
St. Patrick's Day (March 17)
Easter (First Sunday after the first full moon following the spring equinox)
Mother's Day (Second Sunday in May)
Flag Day (June 14)
Father's Day (Third Sunday in June)
Indigenous Peoples' Day (Second Monday in October)
Halloween (October 31)
Election Day (Tuesday after the first Monday in November)

Most US calendars also offer the dates that Daylight Saving Time starts (second Sunday in March) and ends (first Sunday in November).

Please consider adding these. I'm having to refer to another calendar in the meantime.