The New York City Police Department confirmed Wednesday it has increased security around the city this holiday "out of an abundance of caution," following an unsubstantiated report of a terrorist plot against the subway system.

Officials in the Department of Homeland Security said they and the FBI sent a memo to local and state authorities that cited "uncorroborated but plausible information that al-Qa'ida may have discussed in late September the targeting of transit systems in and around New York City."

The NYPD said Wednesday it is aware of the reported chatter among al-Qaeda terrorists, but adds there is no information indicating these discussions had moved beyond the talking stage.

While there are no specifics, Police Commissioner Ray Kelly said it's not uncommon at this time of year.

"There are no specific threats," said Kelly. "We always have to be concerned anytime we have large gatherings; that's precisely what we'll do Thanksgiving Day. We'll have sufficient deployment of officers in my judgment to ensure safety."

All of the local transit authorities including the Metropolitan Transportation Authority, New Jersey Transit, and Amtrak are urging their riders to be alert but said there was no reason for immediate alarm.

"As always, we ask that our customers remain alert and report any suspicious activity or packages, but there is no reason to be alarmed," said the MTA in a statement.

Also, the Department of Homeland Security did not raise its color-coded terror alert level.

The news came as New Yorkers hit the roads, rails, and airports, heading to their holiday destinations. Travelers in Penn Station had mixed reactions Wednesday, as they mingled among policemen armed with automatic weapons and bomb-sniffing dogs.

"This is very scary. I feel like moving out of New York," said one traveler. "And I feel it’s very scary to take the train out of Penn Station, where it's very crowded. Hopefully it's just a threat and nothing else."

"You've heard enough alerts. It's ‘crying wolf,’ is the word,” said another. “I'm not going to worry about it, really. When it happens, I'll duck.”

The Port Authority said it's prepared for a busy travel weekend in the tri-state area.

Officials expect nearly five-million people to go through area airports, bridges, and tunnels.

But for the first time in years, the number of Americans traveling this weekend is expected to decrease as a result of worries about the economy.

AAA expects 41 million Americans to travel more than 50 miles this weekend – a decrease of about 1.5 percent, or 600,000 people. It would be the first drop in Thanksgiving travel since 2002.

Air travel is expected to be down more than seven percent.

The drop in travel comes in spite of rapidly falling gas prices, which are now on average less than $2 a gallon nationwide.

New Yorkers who spoke with NY1 Wednesday morning said despite the bleak economic situation, they are willing to go the extra mile for the holiday.

"Families are supposed to get together and share the thanksgiving dinner together and it's not all the time we get to share a meal together as a family," said one Staten Island resident.

"I have curtailed my driving in the last several months and basically travel overall," said another. "But this is a family tradition, drive up to Cape Cod and enjoy the holiday."

In an effort to keep the city moving, law enforcement officials will be cracking down on drivers who block intersections.

Under a law that took effect in September, blocking the box is now considered both a parking and a moving violation, so traffic agents or police officers can issue tickets to violators. It comes as the city is putting 200 additional traffic agents to work.

"It's estimated that these 200 new traffic enforcement agents will generate about $61 million in revenue and about $66 million here on out each fiscal year, based on, I think it's an average of $83 per summons that the city collects," explained Kelly.

There are seven more Gridlock Alert Days this year after Wednesday, with the next one coming on Wednesday, December 3.

Meanwhile, in observance of Thanksgiving, many closing and schedule changes are in effect around the city.