WASHINGTON - At 3 p.m. Monday, the security cordon began to descend on D.C. "Emergency No Parking" signs went up across the District; by dawn, much of downtown will be under lockdown.

The security hard security cordon extends roughly from 18th Street NW to 1st Street NE, from Constitution Avenue as far north as I Street. No cars allowed. Pedestrians near Pennsylvania Avenue will have to undergo strict security screening: no weapons, strollers, folding chairs, umbrellas and more.

"It will be a lot of pressure," tourist Ben Byers said. There's going to be millions of people here, but I think it'll be alright."

» road closings

» security restrictions

» getting there

» FAQs

To make sure everything is alright, some 20,000 police officers and National Guard troops from around the country have arrived in the city to enforce the massive security zone.

Inside a packed auditorium at American University Monday, more than 4,000 men and women from police departments across the country were sworn in by a U.S. Marshal. They will join the 4,100 members of the D.C. police department.

"It's going to be like another day on the job," said Detroit, Mich., police Chief James Barren, who brought 30 officers to help. " The backdrop is just so significant, I think that's the really greater part of the whole situation."

Since Friday it has been All Hands on Deck for D.C. Police officers. MPD will patrol the D.C. neighborhoods in addition to joining the unprecedented security effort at the Inauguration. That also includes 7,000 National Guardsmen who are already highly visible on the National Mall and city streets.

Police look back at Sunday's opening Inaugural Concert, with an estimated 1/2 million people, and said it was a success.

"Information flowed very, very well [Sunday]," police Chief Cathy Lanier (web | news | bio) said. "We were able to monitor things minute-by-minute. We have a designated radio channel we monitor. And they phenomenal job."

The hope is Tuesday will be as smooth as Sunday. But the crowd is expected to be at least three times is big. Every bridge from Virginia into D.C. is shutdown to everything except authorized vehicles: buses, limousines. Police again are asking people to be patient. The waterways are closed to recreational boats, every commercial vessel -- like the cruise ships -- now have police on board. Helicopters will monitor from above.

Sources say the FBI (web) , Secret Service and D.C. police are hunting down every single tip about possible security threats and so far have turned up nothing credible.

 Email To Friend