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

Release: Banking and Monetary Statistics, 1914-1941  

Units:  Millions of Dollars, Not Seasonally Adjusted

Frequency:  Semiannual, End of Period

Federal deposit insurance began January 1, 1934. The number of insured banks includes some banks which did not submit condition reports and for which, therefore, deposit figures are not included.

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