The West Front of the Capitol during an early morning rehearsal for President-elect Barack Obama’s Inauguration Ceremony in Washington, Sunday, Jan. 11, 2009. (AP Photo/Ron Edmonds)

WASHINGTON — The Secret Service and the region’s top elected officials are defending a decision to block off all Potomac River bridges into Washington and a huge portion of downtown for the inauguration.

At a news conference Tuesday, Secret Service Director Mark Sullivan said “We do not want security to overshadow this event,” but said the closures were necessary.

Sullivan asked that people anticipate delays and inconveniences.

About 3.5 square miles of downtown will be closed to traffic on Inauguration Day. All bridges crossing the Potomac River into Washington also will be closed to vehicles.

Virginia Governor Tim Kaine said authorities aren’t trying to discourage people from attending, but stressed the importance of having a plan before showing up Jan. 20.

On Tuesday, the Secret Service called the Inauguration of Barack Obama an unprecedented security event, with more soldiers, police officers, and road closures than ever before.

Two major highways will be closed, and the parade route is expected to be filled by 10 a.m.   Meanwhile, officials revealed Tuesday that far fewer than the estimated 10,000 charter buses have actually registered to come into the city. 

Maryland Governor Martin O’Malley and Virginia Governor Tim Kaine stood with D.C. Mayor Adrian Fenty Tuesday and offered advice on how to attend the January 20 events.  First, they said, make a plan, study your route, and school yourself on how to get in and out of the city.  Then, they said, pick either the swearing-in ceremony or the parade because you’re not going to be able to do both. 

The governors along with the mayor all said they want people to come and enjoy the festivities, but security is at such a high level that you must be prepared. 

“This is not like throwing the family into the van and heading down to the Air and Space Museum,” said Gov. O’Malley. 
In fact, Governor Kaine announced that Interstate 395 and Interstate 66 will be closed from the Beltway all the way to the Potomac River crossings. 

“If Virginia were to allow unimpeded access of personal and commercial vehicles on 395 and 66 inbound, the Virginia State Police and the Department of Transportation believe that we would experience massive gridlock on the roads,” said Gov. Kaine.

Mayor Fenty says people planning to attend the events of the day should decide on watching either the parade or the swearing-in ceremony, because getting around will make it too difficult to do both. 

Also, Mayor Fenty said only 3,000 charter buses have registered to park in the city, which is far fewer than the original estimate of 10,000. 

“It pretty much means that we will see a lot of registration leading up to the 15th or a lot of people who will still bring buses and not register,” said Mayor Fenty.  “We will over the next several days monitor it, I can say the number of buses registering over the last couple of days has spiked dramatically.”

The Mayor says many of those riders may find the Metro so jammed that they will have to walk from the different bus parking zones.  He says District residents may have to walk. 

“If you are physically able and live within the one-to-two mile radius, I absolutely would encourage you to walk it in from there,” said Fenty. 

The parade route, which is now estimated by the Secret Service to hold up to 350,000 people, is expected to be filled by 10 a.m.—four and a half hours before the parade begins. 

Governor O’Malley encouraged Marylanders to stay off the Beltway on January 20 and use other routes.  MARC trains are sold out, and the VRE trains are 75 percent sold.