If it has no mint mark or a letter P, it's minted in Philadelphia. If it has a D, it's from Denver.
The last silver quarters were minted in 1964.
Simple, no quarters have ever been made in Delaware, the "D" mintmark means it was made in Denver.
If you mean a US Cent, there is a 'D' below the date if it was minted in Denver, Colorado, an 'S' if it was minted in San Francisco, California. If neither of these mintmarks is there, it is from Philadelphia (even today there is no "P" mint mark on US cents) Older Australian cents from the Melbourne Mint don't have mint marks. Those from Perth have a dot between the 2 letters of the designer's monogram (KG).
By looking at the coin. Modern coins made for circulation have the mintmarks on the front. P= Philadelphia. D=Denver.
The D after the date indicates that it was minted in the Denver Mint. An S stands for San Francisco. Higher-denomination coins also have a P for Philadelphia. Cents do not use a P because the sometimes the West Point Mint strikes (comparatively) small numbers of cents when Philadelphia can't keep up with demand. The government doesn't want to create instant rarities, so neither Philadelphia nor West Point cents have mint marks, and you can't tell them apart.
For the year 1853 most all Quarter Eagles were struck at the Philadelphia mint, so they have no mintmark. A few were made at the Denver mint and will have a "D" mintmark.
It's the year that the coin was minted. If you look under the date you can tell where it was minted, too: "D" = Denver Mint "S" = San Francisco No letter = Philadelphia
In the US, there will be a mint mark on the coin if it was minted in Denver or San Francisco (the letter D or S respectively). If there is no mint mark, it was minted in Philadelphia. The exception to this is that coins minted from 1965-67 don't have mint marks even if they were minted outside of Philadelphia, so for those years you can't really tell.
The Denver Mint peace dollar will have a "D" mint mark located on the reverse side, near the tail feathers of the eagle. The Philadelphia Mint peace dollar will not have a mint mark, as the Philadelphia Mint did not mark its coins with mint marks during that time period.
On the back of the coin under the "O" in "ONE" there should either be no mark, a D or an S. If your coin has no mark, it was minted in Philadelphia. If it has a D it was made in Denver and if it has an S it was made in San Fransisco.
US coins dated 1965-1967 don't carry mint marks, so it's not possible to tell where your quarter was minted. In circulated condition it has no added value -- there is no silver in it. A nice uncirculated one is worth about 50 cents.
Many U.S. coins have a mint mark to show where it was minted. On modern quarters, the mark is just to the right of Washington's hair ribbon. P stands for Philadelphia, D is Denver, S is San Francisco, and on older quarters there is O for New Orleans. On quarters minted before 1980, there was no mint mark for Philadelphia. For silver Washington quarters dated 1964 and earlier, Barber quarters, and Seated Liberty quarters, the mark is on the back just below the eagle. Then with Standing Liberty quarters, the mark is on the front, just above and to the left of the date.
The last silver quarters were minted in 1964.
The 1943 Wheat Cent was made of steel.Very few of these coins are known to have been made of copper. To determine where the coin was minted it is necessary to locate the mint mark. This mark is a small letter located just below the date. If there is an "S" there the coin was minted in San Francisco. If there is a "D" the coin was minted in Denver. If there is no letter below the date the coin was minted in Philadelphia.
The 1943 Wheat Cent was made of steel.Very few of these coins are known to have been made of copper. To determine where the coin was minted it is necessary to locate the mint mark. This mark is a small letter located just below the date. If there is an "S" there the coin was minted in San Francisco. If there is a "D" the coin was minted in Denver. If there is no letter below the date the coin was minted in Philadelphia.
All Jefferson nickels for circulation were minted at Philadelphia, Denver or San Francisco. The mint at West Point has, in the past, minted coins for other US mints but did not put a West Point mint mark on the coins so there is no way to tell which ones were made there.
The "S" and "D" are called mint marks. They tell us where the coin was minted. San Francisco and Denver are the locations of the U.S. Mints, along with Philadelphia. Philadelphia has no mint mark to identify it. Can you guess which of the mints is identified by the S and which by the D?