What is the value of a 1900 US silver dollar?

Answer:

This coin is often called a Morgan dollar, after its designer George T. Morgan.

1900 is not generally a rare date for Morgan Dollars. Look on the back of the coin to see if there's a small mint mark letter above the DO in DOLLAR. It may be blank or there may be an O or S. If it has an "O", then take a good magnifier and closely examine it for traces of a "CC" mintmark around the "O" -- this is a scarcer variety.

Numismedia lists the following approximate retail values as of 04/2011:

No mint mark (Philadelphia):
Very worn condition - $32
Moderately worn - $33
Slightly worn - $34
Almost no wear - $36
Uncirculated - $42 to $7,310 depending on quality

"O" mint mark (New Orleans):
Very worn - $32
Moderately worn - $33
Slightly worn - $34
Almost no wear - $36
Uncirculated - $42 to $4,280

"S" mint mark (San Francisco):
Very worn - $32
Moderately worn - $33
Slightly worn - $34
Almost no wear - $82
Uncirculated - $290 to $18,750

If you have the scarcer "O over CC" mintmark, the values are even higher --
Very worn - $33
Moderately worn - $48
Slightly worn - $67
Almost no wear - $188
Uncirculated - $300 to $27,250

DISCLAIMER: The retail values quoted are the best available as of the date shown, but may vary significantly due to changes in the precious metals market. Also the wholesale (buying) price of a coin will be less than the selling (retail) price. A reputable coin dealer will be able to give a more accurate valuation based on inspection of the coin.

FAQ's about Morgan dollars

E Pluribus Unum
The motto E Pluribus Unum (Latin for "Out of Many, One") is on ALL $1 coins minted since 1878 so that's not specific enough to ID any one coin.

Silver Eagles
Silver eagles are bullion coins minted since 1986 for sale to collectors but not for spending. Morgan dollars were made for use in ordinary circulation just like dimes and quarters.