Shoghi Effendi sent verbal messages through Consul Schwarz to Germany and Ethel Rosenberg to Britain to form local spiritual assemblies and to arrange for the election of a national spiritual assembly in each country. [CB293; ER209, 211-12; PP56]
To the United States and Canada Shoghi Effendi sent a message to transform the 'Executive Board' into a legislative institution. [CB293; CT160; ER211-12; PP56]
It had been functioning since 1909 concerned mostly with the construction of the Bahá'í House of Worship.
He addressed his first letter to this body as the "National Spiritual Assembly of the United States" on December 23rd however in God Passes By pg333 he stated that the National Spiritual Assembly of the United States was not formed until 1925. [SETPE1p107, CT160, CoB293]
A National Spiritual Assembly was elected in the United States to replace the Executive Board of the Bahá'í Temple Unity. [SBR94]
The difference between this body and its forerunner was little more than a change in name. [DP122]
The conversion of the Bahá'í Temple Unity into the National Spiritual Assembly took four years; it was not until 1925 that Shoghi Effendi recognized the American national body as a National Spiritual Assembly. [CT161; DP121-2; GPB333]
The election procedure followed that used in the United States and not the current Bahá'í procedure: there was electioneering and candidates were nominated, with a straw poll taken to trim the number of eligible candidates. [CT160; DP122]