Remember the Susan B. Anthony dollar, the Edsel of American coins? Haven't seen many lately, have you?

That's because they're all underground in Baltimore's new Metro subway system.

Well, maybe not all of them, but a good 60,000. Another 800 million or so are floating around somewhere else.

Baltimore opened its subway last November with a set of change machines that give out Susan B. Anthony dollars, rather than more conventional nickels, dimes and quarters, in exchange for paper money. The "Susan B.'s," as they affectionately are called hereabouts, are used to purchase subway tickets.

Baltimore is one of the few places where Susan B. Anthony dollars are used in bulk quantities. Up to 60,000 are stored in 12 big console changers at the subway's nine stations, giving Baltimore the largest single stack of Susan B.'s in the free world.

"Theoretically," said Baltimore Metro engineer Bill Kirkpatrick, "the Susan B.'s stay in the system," circulating from the change machines to the ticket dispensers and back to the change machines in a self-replenishing cycle. A few slip out of the system, Kirkpatrick said, taken by souvenir hunters and the occasional Susan B. Anthony worshiper.

To keep the system stocked, local commercial banks and the Federal Reserve Bank in Baltimore have a bounteous supply of Susan B. Anthony coins on hand: bags and bags and bags and bags of them, because no one else much wants them.

Most places that have tried Susan B.'s in volume have given up. A suburban Philadelphia commuter service, the Port Authority Transit Corp. still uses them. The Astroworld amusement park in Houston has a few, "but that's about it," said Frank DeLeo of the Bureau of the Mint, which watches such things.

"A couple of toll bridges in New York tried them for awhile, but dropped them," DeLeo said. Even gambling casinos, which bought specially designed slot machines for Susan B.'s when they first came out five years ago, largely have abandoned the coin.

"They're not very popular," said Harry Okin, director of slot operations at Caesar's Boardwalk Regency Hotel Casino in Atlantic City. "They're too easily confused with quarters."

So where have all the Susan B. Anthony dollars gone, if they're not in Baltimore?

Most of them--approximately 500 million, give or take a million or two--haven't gone anywhere. They are in "inventory," which is the government's way of saying they're lying around unused in vaults of the Bureau of the Mint and the 37 Federal Reserve banks across the country.

Another 330 million theoretically are in circulation, although specialists ranging from Treasury Department officials to private numismatists aren't sure where they've gone.

"A lot of the general public looked at them as a kind of oddball coin when they first came out, and put them aside," said Edwin C. Rochette, executive vice president of the American Numismatic Association.

"If only one in every 10 people put a couple aside, you're talking about millions that are now in a sock drawer somewhere," Rochette added.

The coin, with the head of the famed suffragist depicted on one side, first was minted in 1979, but never really caught on as an alternative to the dollar bill. The Bureau of the Mint turned out more than 830 million of the coins, but most sat unused as government efforts to ignite national passion for the coin sputtered out one by one.

"Not exactly a groundswell of enthusiasm," acknowledged mint spokesman John Doom. Minting of the coin was discontinued in 1981.

But, at least in the Baltimore subway system, Susan B.'s are the coin of the realm.

The idea is to put a dollar bill into the change machine, get a Susan B. in return and then put it into a separate ticket-dispensing machine for the subway ticket. You may or may not get back some small change, depending on the length of the trip or number of rides purchased.

Transit engineers say that separate change-making and ticket-dispensing machines help limit mechanical breakdowns. Most other rail transit systems, including Washington's, combine these functions in one machine. CAPTION: Pictures 1 and 2, Passengers using Baltimore's new Metro must insert dollar bills in vending machines to get $1 coins with which to pay fo subway rides. Photos by Dudley Brooks--The Washington Post