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

Release: H.4.1 Factors Affecting Reserve Balances  

Units:  Billions of U.S. Dollars, Not Seasonally Adjusted

Frequency:  Weekly, Ending Wednesday

Currency in circulation includes paper currency and coin held both by the public and in the vaults of depository institutions. The total includes Treasury estimates of coins outstanding and Treasury paper currency outstanding. This definition of currency in circulation differs from the currency component of the money stock, a measure of currency used in some other Federal Reserve reports (for example, the H.6 release), which excludes currency held in vaults of depository institutions.

1984-1985 and Jan 11-Mar 15, 1989: Annual Statistical Digest 1984, 1985, 1989 Table 2.
Jan 8, 1986 to date except weeks ending Jan 11, 1989 - Mar 15, 1989: Federal Reserve Board H.4.1.