Source: Board of Governors of the Federal Reserve System (US)  

Release: Banking and Monetary Statistics, 1914-1941  

Units:  Number, Not Seasonally Adjusted

Frequency:  Semiannual, End of Period

Notes:

For June 1914 (before the Federal Reserve Banks commenced operation), the figures for "member" banks represent all national banks in the continental United States, while those for "nonmember" banks represent all State banking institutions (Excluding unincorporated or "private" banks not reporting to State banking authorities) in the continental United States.

Figures exclude those unincorporated or "private" banks not reporting to State banking authorities, except the figures for noninsured banks are residuals derived by subtracting the figure for insured banks from the total.

Banks in United States possessions are excluded except one national bank in Alaska; which was a member of the Federal Reserve System from the time it opened for business in April 1915 until it was placed in voluntary liquidation in April 1921 and which in June 1919 hud total deposits of $351,000.

For more information, see Table 1 at https://fraser.stlouisfed.org/scribd/?item_id=6408&filepath=%2Fdocs%2Fpublications%2Fbms%2F1914-1941%2FBMS14-41_complete.pdf&start_page=1