May 15

Each city will have its own Spiritual Assembly, not a number of district ones. Naturally, district Nineteen Day Feasts can be held where there are very many Bahá'ís in one city. 
- Shoghi Effendi  (From a letter written on behalf of Shoghi Effendi, 31 March 1949 to an individual believer; The Compilation of Compilations, vol. I, The Nineteen Day Feast)