October 9 came and went with New York City’s transit system safe from attack.

A Department of Homeland Security memo had warned that terrorists might strike the subway “on or about October 9.”

The validity of the claim has been the subject of much debate since last Thursday, when Mayor Bloomberg, his police commissioner, and an investigator from the FBI announced that New York could be the target of an impending terror plot.

While the city has beefed up its security measures in the transit system, the Department of Homeland Security has questioned the credibility of the tip.

A department spokesman, Russ Knocke, was quoted by the Associated Press as saying yesterday, “The intelligence community has been able to determine that there are very serious doubts about the credibility of this specific threat. This is after ongoing review and analysis.”

The police commissioner, Raymond Kelly, yesterday told CNN’s “Late Edition” that investigators would find out if there was “real substance” to the threat. In the meantime, Mr. Kelly told the news channel, the authorities are investigating whether any of the alleged terrorists scheming against the subway system are actually in America.

While it was unclear how the threat has affected ridership, straphangers and people working in businesses inside the transit system expressed some concern about their safety but essentially said life had to keep going.

Randy De La Cruz, who works Saturdays and Sundays at a Petal Pusher cart selling fresh flowers in Penn Station, traveled from Brooklyn on the F and A lines to arrive at work at 10 a.m. yesterday. “There’s been a lot of threats,” Mr. De La Cruz said to rationalize his lack of fear. But, he said, “of course I’m going to be cautious.”

One of Mr. De La Cruz’s customers, Lydia Klein, came from Long Beach to meet her boyfriend in the city. She explained her reasoning for continuing her regular activities: The terrorists win “if we stop doing things.” Numerous people echoed her position.

The newest terror threat did not raise fresh fears in Ms. Klein. “I’ve been concerned since September 11,” she said.

Early yesterday afternoon, an employee at the Carvel and Cinnabon store in Penn Station, Alma Alarcon, said sales were down for the day because “I think less people are traveling around.”

One woman who lives in Tudor City said she was used to living under the threat of terrorism. “I’m not concerned,” Kate Hughes said while waiting in Grand Central Terminal. “I grew up in England, where they have quite a bit of terrorism.”

To Ms. Hughes, being killed by a terrorist seems unlikely. “If I get killed in New York City,” she said, “I’m going to get run over by a bus.”

Bag searches were fairly frequent yesterday afternoon at the entrance to a Penn Station subway line. Rather than wait to see if they would be called upon to open their bags, many straphangers were offering to show their belongings to the officers.

Nick Guerette, who lives in Seattle and was visiting his father in New York, walked up to the officers and eagerly put his bag on the table. “I figure it’s kind of necessary,” he said. Because a check could have been required, he figured he would “not make it difficult.”

One Boston resident, Kelsey Brunone, who the officers summoned over for a bag check, said, “I had a big bag. I just knew they’d stop me.”

Regardless of whether the threat turns out to be credible, Senator Schumer said the city took the right precautionary steps. In a “post-9/11 world,” the senator said at a press conference yesterday morning in the Union Square subway station, “you can’t be too careful.”

Mr. Schumer sharply criticized the reduction in security funding for the city’s mass transit system at a time when the system “has become the terrorist target of choice.”

While the city received more actual mass transit security dollars compared to the last two fiscal years, the city’s share of the federal pot in fiscal year 2005 shrank to 27% from 35% last year and 46% the previous year. The Metropolitan Transportation Authority, New Jersey Path, the New York City Department of Transportation, and Staten Island Railway received $37.6 million in federal mass transit security funding in 2005; the national total was $141 million.

The security funding translates to one penny for each mass transit rider, Mr. Schumer said, while $7 is allocated for each air passenger.

As the fear of a possible attack lingered yesterday, Mr. Schumer said, “I feel safe riding the subways. New Yorkers should still feel safe.” To prove it, he took a subway ride – with a couple of police officers, his staff, reporters, and photographers in tow – up to 42nd Street from Union Square.