It's on the reverse between the tip of the eagles tail and below the word one near the rim.
1928 makes it a Peace dollar. The mint mark is located on the reverse (tails) side, below the word "one." D for Denver, S is San Francisco, and no mark is Philadelphia.
The mint mark on any Morgan dollar is on the reverse above the letters DO in dollar.
If the 1928 Peace dollar has no mint mark, circulated coins have retail values of $275.00-$430.00 depending on the grade.
If the 1928 Peace dollar has no mint mark, circulated values are $290.00-$450.00 depending on the grade
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If it has one, it's on the reverse above DO in the word dollar.
For Morgan silver dollars, the mark is on the reverse (tails) side, just above the letters "do" in "dollar." Then on Peace dollars, the mark is also on the reverse, below the word "one."
$22 to $75,000 depending upon the mint mark and the condition of the coin.
If it has one, it's on the reverse above DO in the word dollar.
If there is one it's on the back above the letters DO in the word dollar.
If there is one it's on the back above the letters DO in the word dollar
If it doesn't have a mint mark, that means it was made in Philadelphia.