It should be clear by now: No drinking on the subway. If you’re on the Metro-North Railroad, though, cheers, drink up.

While they’re both subsidiaries of the Metropolitan Transportation Authority, these two forms of mass transit are worlds apart, as the MTA board made clear last week when it passed new subway rules and reiterated its ban on open containers in subway cars.

On the Metro-North, the Long Island Rail Road, and New Jersey Transit commuter railroads, as well as on the Staten Island Ferry, drinking alcohol is not only legal, it is encouraged.

At Penn Station, New Jersey Transit and LIRR customers need only keep their can of beer in a brown bag until they get on the train. The LIRR used to sell alcohol on the trains; on the ferry, beer is sold alongside soda and chips.

Nowhere is the culture of the 5 o’clock martini so ingrained as on Metro-North, where alcohol has been served on bar cars since the days of the Penn Central Railroad, which went bankrupt in 1976.

Today, the commissary is the railroad’s only department that generates a profit, the man in charge of serving alcohol to the public, Thomas Celli, said. Sales have increased along with the ridership, which topped 72.4 million passengers in 2004, a record.

The commissary is located trackside on the lower level of Grand Central Terminal. It is run by Mr. Celli, a jovial man with a full-bodied laugh who looks and acts younger than his 51 years. After 31 years in the business of serving drinks for the railroad, Mr. Celli still sings the jingles of beer companies long since eclipsed by other brands, remembering a more easygoing era of drinking.

“‘Schaefer is the one beer to have, when you’re having more than one,'” Mr. Celli said in a singsong cadence during a recent interview. “That was when you could drive drunk,” he said, laughing. “I’m teasing, you could never drive drunk.”

Clearly, though, the days when beer slogans read like a bartender’s last call have passed.

The drinking habits of the riding public have changed as well.

The martini and the scotch and soda have been replaced by the vodka tonic and bottled water, the overall top seller since it was introduced several years ago.

In 1974, when Mr. Celli was a bartender on the bar cars, the railroad catered to high-powered Wall Street executives, many of whom rode home, playing poker or pinochle in private club cars, scotch in hand. Here, bartenders were handsomely tipped for fetching dry cleaning or bringing their own olives for gin martini drinkers who liked their drinks served dry, with little vermouth.

“Just open a bottle over it, kid,” Mr. Celli recalled his customers saying. At that time, though, whiskey dominated.

“And when I say dominated, I mean dominated,” Mr. Celli said. “We were a whiskey-pouring group in those days.”

In the summer, gin and tonic became the drink of choice. It went well with the seersucker suits and straw hats, Mr. Celli said. And, unlike today, there were many gins in the bar car to choose from.

In 1976 Conrail, which took over the bankrupt Penn Central, did away with the class distinctions created by private bar cars.

While the tradition of serving alcohol on the rails has survived since Metro-North was created in 1983, the habit of drinking scotch has not.

“Vodka’s the scotch of yesterday,” Mr. Celli said.

Today’s drinkers “don’t want to kiss the missus with alcohol on their breath,” he said. “The scotch drinkers, they didn’t give a hell.”

Through mid-June, the railroad had gone through 30,658 bottles of the brown liquors, compared to 32,289 of Absolut vodka alone.

Wine coolers were once served, but, Mr. Celli said, they “went out with disco,” to be replaced by specialty drinks like Mike’s Hard Lemonade.

The bar cars are something of an endangered species, with only 10 remaining on Metro-North trains. All are on the New Haven line and are owned and maintained by the state of Connecticut. Most are in disrepair. Loyal drinkers have had to fight to convince transportation authorities not to replace them with cars that can carry more passengers, as happened in 1983 on the New York State lines.

These days, bar cars are windowless, the bars are plastic, and the flooring is vinyl.

That didn’t seem to matter to commuters on a recent ride to New Haven. Happy hour began at 6:58, when the train pulled out of Grand Central Terminal.

“If you take a bar car, it’s like a comedy club,” one rider, Bill D’Arbanville, said.

The ban against open containers is considered a safety measure to protect riders on crowded and jarring subway rides, an MTA spokesman, Tom Kelly, said.

Mr. D’Arbanville, however, sipped from his can of Miller Lite and compared the subway authority to those in Connecticut who want to shut down the bar cars.

“Everybody’s bothered by everything,” he said.