There is a red mark on the dollar.

On dollar bills, we can often see various marks made of letters, numbers or patterns. Some of them are used to identify the authenticity of dollar bills, while others are even used to promote religious beliefs. * Generally, there is a slogan "In God We Trust" in a prominent position in the US dollar (coins are just below the heads of characters, and those on paper money are generally above the negative center line). This inscription first appeared on a two-cent coin in 1864. Since 1955, Congress has made it a legal national slogan. Today's law stipulates that this slogan must be used on all American coins and paper bills. The first paper banknotes appeared in 1 yuan's "silver notes" issued in 1957, and began to appear in the "Federal Reserve Notes" issued in 1963. * TREASURY SEAL. The US Treasury seal is printed on the bottom of the US dollar bill, and the treasury seal of the federal reserve certificate is printed on the right. Other coupons are printed on the left in 1928, and will be printed on the right since the 1934 edition. In the early days, the library seal was circular, with 4 teeth on the periphery, and each tooth was even in thickness. There was a Latin word "THESAUR AMER SEPTENT SIGIL" in a circle, and the center of the circle was a shield. The shield was divided into upper and lower parts by an inverted V, and the upper part was a balance, with 32 dots around it, 13 five-pointed stars in the inverted V, a key in the lower part and a keyhole. Since the 1969 edition, the library seal has been further simplified, and the text has been changed to English "The Department of the Treasury, 1789" (Ministry of Finance, 1789), and the pattern on the periphery of the shield has been cancelled, with 22 dots in the upper part, 17 dots in the lower part and 39 dots in * * *. The 1928 and 1934 editions were big library prints with a diameter of 2 mm, and the 1935 edition and subsequent editions were all changed to small library prints with a diameter of 16 mm, and the patterns and characters remained unchanged. There are five colors of library printing: green, blue, yellow, red and brown, which are different according to the types of coupons. Above the library seal is the place name of the capital "WASHINGTON,D.C" Different versions of American banknotes in history. Before the Declaration of Independence was published, the United States had already used banknotes. The history of American currency can be traced back to 169. The Massachusetts colony issued the first currency to make up for the cost of military expedition. This practice was quickly spread to other colonies. However, due to the easy wear and tear of hand-carved copper plates, it was impossible to maintain the consistency of finished products. As a result, criminals had an opportunity, and eventually counterfeit banknotes flooded everywhere, so these tickets were quickly abandoned. * In 1764, after years of restrictions on the currency of the North American colonies, the British authorities finally issued a ban on the issuance of currency by the colonies. Later, due to the war of independence against Britain, North American colonies consumed a lot of funds, and a large amount of gold and silver were collected by Britain as taxes, which led to the lack of domestic funds in the United States. In order to raise funds, the Continental Congress of the Union Power of 13 colonies held talks in Massachusetts on May 1, 1775, and on June 22, 1775, it approved the issuance of a paper currency convertible into Spanish silver dollars with a total value of US$ 2 million, called Continental Congress. However, due to the emergence of counterfeit banknotes soon, its value is so small that it is called "not as good as a mainland coin" in the saying. In 1781, it was replaced by a bank note (that is, paper money issued by a bank and freely convertible into metal currency within the bank). * On December 31st, 1781, the Bank of North America in Philadelphia became the first national bank and was granted a banknote issuing concession. After the American Constitution was published in 1789, the Bank of new york and the Bank of Providence were also chartered to issue currency (until 1836). On July 6, 1785, Congress officially adopted the Dollar as the legal tender unit. In 1791, Congress chartered "Bank of America" as the treasury agent of the US Treasury for 2 years. It was the first bank to perform the function of central bank for the government, and it operated until Congress refused to renew its charter in 1811. Realizing that a central banking system must meet the needs of national finance, Congress chartered the second "Bank of America" to have another 2-year agent in 1816. In 1877, the Bureau of Plate Making and Printing of the Ministry of Finance began to print all American currencies. * In 1861, in order to raise the cost of the Civil War, Congress legislated to authorize the Ministry of Finance to directly issue 45 million yuan of "Demand Notes" that were not guaranteed by coins and gold. For the purpose of preventing counterfeiting, it uses green ink that is difficult to copy by photography (silver halide sensitizer is the least sensitive to green light). Due to technical reasons, the back of the banknote is darker than the front, so it is called "greenback" (today, we still call the dollar by this name). Strictly speaking, this is the first popular American currency. It is called a federal bond, which is also called a United State Notes. Its library number and serial number are all red. Each "sight bill" is signed by the agent of the registrar of the Ministry of Finance and the federal treasurer. This unrealistic measure has inspired new laws and regulations that allow registrars and finance ministers to print signatures on currency. This measure was implemented in the first series of government bonds issued in 1862. * According to the American legislation in 1861, the TREASURYNOTE was issued by the Ministry of Finance. There were only two versions, the 189 and 1891 versions, with which silver and gold could be purchased at that time. * During the period from 1862 to 1864, the National Bank Law allowed banks designated by each state to issue paper money with US Treasury bonds as reserve, which was called NATIONALCURRENCY, and the serial numbers were all brown, also called National Currency or National Circulation Bill. There are many kinds of these banknotes, about 16 state-owned and private banks issue money, and more than 7 kinds of legal tender with different faces. In 1863, all private banks and state banks chartered to issue banknotes were required to join the national banking system or pay a 1% banknote issuance tax. In 198, a supplementary bill was added to allow the National Bank to issue paper money with bonds other than US Treasury bonds as reserves. Later, two main versions of the national bonds were formed by the Federal Reserve Bank and the National Bank: the version issued by the National Bank has a serial number of 6 digits, and two or four large black numbers are printed on the right and left sides of the front, and the other serial number is 8 digits; The name of the Federal Reserve Bank is printed on the left side of the front of the banknote, and four letters representing black areas are printed on the left and right sides, which are issued by the Federal Reserve Bank. The earlier issuance of national bonds was signed by four responsible persons, the two upper corners were signed by the Minister of Finance and the Treasury Director, and the two lower corners were signed by the cashier and the president. The coupon was withdrawn and no longer issued on July 1, 1935. After 1928, a 1929 edition was issued, which was a $66 million banknote issued by the U.S. Treasury in December 1942 in the form of national vouchers to raise military expenses during the Second World War. * In order to redeem gold, the U.S. government began to issue GOLD CERTIFICATES in 187, and the serial number is yellow, also known as gold certificates. The face of the coupon is printed with the words "the holder can exchange gold coins with it". It is a currency prepared with 1% gold issued by the US Treasury. From the end of the Civil War to 1933, gold coin coupons were freely convertible into gold coins and circulated in the market as part of the American money supply. In 1931, with the collapse of the gold standard, gold coin coupons stopped being exchanged for gold in 1933. * In order to prevent silver from being smuggled abroad, the United States began to issue SILVERCERTIFICATES in 1878. The library seal and serial number are blue, also known as silver dollar coupons. It was issued according to the laws passed in 1878 and 1886, and it can be exchanged for equivalent silver coins. Later, due to the increase of silver price, from June 24, 1968, silver dollar coupons could not be exchanged for silver. In addition, there is a kind of silver coin coupon with blue serial number printed in yellow library, which is a military ticket used by American troops in North Africa during World War II. Yellow seal is different from blue seal in case it falls into enemy's hands. After the war, many yellow-printed tickets were widely circulated and have been used as other types of tickets. * During the Korean War, the United States issued a military ticket in South Korea, with the words "reimbursement voucher for military war zone" printed on the ticket face, which was limited to use in the war zone and was not used for general currency circulation. This kind of ticket was declared invalid on May 25th, 1954. In addition, there are HAWAIIan coupons, which are not independent coupons. Instead, the black word "HAWAII" is printed on the existing coupons (federal reserve coupons and silver coin coupons), and the hollow "Hawaii" in larger font is printed horizontally in the middle of the banknotes on the back. The library seal and serial number are brown. Originally used in the Hawaiian islands, it was later circulated everywhere. All kinds of banknotes issued from 1861 to 1928 mentioned above have a large bill size of 178mm×73mm, regardless of the type and denomination. The US Treasury Department ordered that they be withdrawn in 1922, but they are still legal tender in the United States and can be exchanged with American banks. On December 23rd, 1913, the US Congress passed the federal reserve act and established the Federal Reserve System. According to the provisions of the "Act", the whole country has divided 12 federal reserve areas, and each area has set up a federal reserve bank in a designated central city (federal reserve city), and there are 12 federal reserve banks in the whole country to exercise the functions of central banks, so that there are 12 federal reserve banks in the United States. In Washington, D.C., the Federal Reserve Board was established as the highest leading body. On November 16, 1914, the Federal Reserve Bank began to issue FEDERAL RESERVEBANK NOTES as legal tender in exchange for National Bank Notes. From June 12, 1945, such notes were withdrawn and no longer issued. At the same time, a kind of FEDERAL RESERVE NOTES was issued as a large number of common currency in daily life. According to the regulations, the federal reserve bonds should be adequately guaranteed, and the collateral is gold or government bonds, senior or short-term commercial securities. Its serial number and library print are green. At present, 99% of what we have access to are federal reserve bonds, and others are a small amount of government bonds and silver coins.