With engines idling, brake lights blinking and drivers fretting, thousands of automobiles clogged the streets of downtown Washington last night as traffic problems connected with inaugural festivities all but brought the evening rush hour to a complete, horn-honking halt.

"It's the worst mess I've ever seen," said a red-vested D.C. police officer as he tried to dissolve the vast clot of cars at 17th Street and Pennsylvania Avenue NW, one of the key pressure points during a seemingly endless rush hour.

Echoing this assessment of the jam, other officers said it appeared to stem from the closing of E Street NW and Constitution Avenue NW behind the White House for security and safety reasons for a pageant held on the Ellipse.

Those and other street closings and parking curbs in the White House area enmeshed traffic in a severe snarl that police said was only compounded by the mingling of homebound commuters with motorists hoping to attend the pageant.

"People are driving in circles," said Sgt. A.W. Miles. A motorcade carrying Vice President Bush down Connecticut Avenue to the pageant, and a later salute to him at the Convention Center, made motorists' misery worse, Miles said.

"A snail's pace," said an officer when asked to gauge the rate of traffic along 17th Street at 7 p.m., three hours after the the crush began. On the other side of the Ellipse, a man in a pickup truck said a trip of 1.6 miles had taken more than an hour.

At the wheel of a car with out-of-town plates, a man headed for the pageant merely chuckled when asked if he had been delayed. A woman next to him seemed less resigned.

"We missed the whole thing," she said. "I'm a nervous wreck."