President's Day
June 22, Sunday

Historical context
The exact reason for choosing this date is not widely publicized, but it may be linked to significant political events in the country's history. A referendum held on June 14, 1964, and the subsequent re-election of François "Papa Doc" Duvalier as president for life on June 22, 1964, is a well-known event in the country. Possibly, the date became a tradition as a symbol of stability or authority.
What accompanies the holiday?
Official details for this day are scarce in sources, but generally it may include:
* official addresses from the head of state or government;
* ceremonial events and wreath-laying;
* media publications on the role of the presidency and statehood.
Coincidence with a religious holiday
Interestingly, June 22 sometimes coincides with the feast of Corpus Christi, which may add a religious element to the national day.
Conclusion:
June 22 is observed in Haiti as the official President's Day, which likely has political and historical roots in the Duvalier regime era and may at times coincide with a religious celebration.