The principal issue of United States paper money was officially called United States notes. These were the well-known "greenbacks" or "legal tenders." The act of February 25, 1862, authorized the issue of $150,000,-000, of which $50,000,000 were in lieu of an equal amount of demand notes, and could be issued only as the demand notes were canceled. A second issue of $150,-000,000 was authorized by the act of July 11, 1862, of which, however, $50,000,000 was to be a temporary issue for the redemption of a debt known as the temporary loan. A third issue of $150,000,000 was authorized by the act of March 3, 1863. The total amount authorized, including the temporary issue, was $450,-000,000, and the highest amount outstanding at any time was $449,338,902 on January 30, 1864. There are still outstanding $346,681,016.

The reduction from the original permanent issue of $400,000,000 to $346,681,016 was caused as follows: The act of April 12,1866, provided that United States notes might be retired to the extent of $10,000,000 during the ensuing six months, and that thereafter they might be retired at the rate of not more than $4,000,000 per month. This authority remained in force until it was suspended by the act of February 4,1868. The authorized amount of reduction during this period was about $70,000,000, but the actual reduction was only about $44,000,000. No change was made in the volume of United States notes outstanding until after the panic of 1873, when, in response to popular demand, the Government reissued $26,000,000 of the canceled notes.

This brought the amount outstanding to $382,000,-000, and it so remained until the resumption act of January 14, 1875, provided for its reduction to $300,000,000. The process was, however, again stopped by the act of May 31, 1878, which required the notes to be reissued when redeemed. At that time the amount outstanding was $346,681,016, which is the present amount. The amount of United States notes redeemed from the fund raised for resumption purposes since January 1, 1879, to June 30, 1908, was $680,581,146; but the volume outstanding is undiminished because of the provisions of the act of May 31, 1878, which require the notes so redeemed to be paid out again and kept in circulation.

The act of March 14,1900, also directed the reissue of United States notes when redeemed, but they must first be exchanged for gold as provided in the said act. The act also provides that when silver certificates of large denominations are canceled, and small denominations issued in their place, a like volume of small United States notes shall from time to time be canceled and notes of $10 and upward issued in substitution therefor.