Dollar (abbreviation: USD；; Zhai O 42 17 currency code: USD; ; Symbol: USD) is the legal tender of the United States of America. At present, the US dollar banknotes in circulation are all the banknotes issued since 1929.
1792 appeared after the passage of the American mint act. At present, the issuance of US dollars is controlled by the Federal Reserve system. Starting from 19 13, the United States established the federal reserve system and issued federal reserve bonds. More than 99% of the banknotes in circulation are federal reserve notes.
The competent department for issuing US dollars is Congress, and the Federal Reserve Bank is responsible for the specific issuance business. After World War II, continental European countries reached an agreement with the United States to use US dollars for international payments. Since then, the dollar has been widely used as a reserve currency in countries outside the United States, and eventually became an international currency.
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Dollar notes are made of cotton fibers and hemp. Long cotton fiber makes paper not easy to break, good ink absorption and not easy to fade. Hemp fiber is tough, which makes the paper stiff for a long time and has certain resistance to water, oil and some chemicals. One-dollar paper is white without whitening agent and does not reflect light under purple light. Since 1880, there have been red and blue fibers in the paper of dollar bills, which are mixed with pulp when making paper. So some fibers are sandwiched in the paper and some float on the surface, and the fibers can be picked out with the needle tip. Before 1928, red and blue fibers were distributed in the middle of banknotes, and they were long and narrow up and down.
1928 and later versions, full-page transmission of fiber silk. Starting from 1990, a safety thread made of polyester polymer called Myra was added to the dollar paper (as shown in the left). The security line has dollar symbols and denomination figures, which can be seen clearly through perspective. The ink on the front of the dollar is black, slightly dark and slightly gray, and the back is green.
In the version after 1934, magnetic substances were added to the ink, and the magnetic real US dollar bills were specially made with special inks such as fluorescent ink and magnetic ink. Therefore, the green emblem and green numbers on the right side of the front of the US dollar bill can leave "green marks" on the paper after hard wiping. Some US dollars issued after 1996 will show black and green at different light angles. The main pattern of the dollar is engraved intaglio printing, and the library printing and serial number are embossed printing. After version 1990, there are micro characters around the portrait window below.
References:
Baidu Encyclopedia-USD