What is the value of a 1918 US quarter?

Answer 1

Look at the pedestal on the left-hand side of the coin, above and to the left of Miss Liberty's right foot to see if there's a small mint mark letter. [The "M" on the other pedestal is the designer's monogram, not a mint mark.]

Numismedia lists the following approximate retail values as of 02/2010:

No mint mark (Philadelphia):

Very worn condition - $17

Moderately worn - $26

Slightly worn - $31

Almost no wear - $83

Uncirculated - $138 to $3,910 depending on quality

"D" mint mark (Denver):

Very worn condition - $29

Moderately worn - $46

Slightly worn - $70

Almost no wear - $176

Uncirculated - $258 to $5,690

"S" mint mark (San Francisco):

Very worn condition - $18

Moderately worn - $33

Slightly worn - $44

Almost no wear - $115

Uncirculated - $210 to $3,810

However, there is also a variety of this coin with an S mint mark and an "overdate" that occurred when an engraver reused a 1917 die. If there is a 7 visible underneath the 8, it's worth anywhere from $1600 to $100,000, but a professional appraiser needs to certify the coin as a genuine overdate.