Heavy security grips U.S. capital for inauguration day

A police officer stands guard in front of the Capitol  building in Washington Jan. 18, 2009. U.S. authorities  are tightening up security in the capital city ahead of  the Jan. 20 inauguration of President-elect Barack Obama.  (Xinua/Zhang Yan)

An estimated 2 million people will swarm downtown Washington and set a record that could diminish the number of attendees at any previous presidential inaugurations.

Struggling to meet the soaring security needs, the Secret Service has assembled a formidable security force of more than 40,000 people, including 7,500 active-duty soldiers, 10,000 National Guard troops and 25,000 law-enforcement officers.

They will constitute the largest-ever security force assembled in the nation's capital, surpassing the 31,000-member U.S. troops serving in Afghanistan, according to U.S. media reports.

With the swearing-in ceremony starting at 11 a.m. Tuesday, the authorities have advised would-be participants and spectators to arrive hours earlier for security checks.