South Street, long one of Philadelphia's most popular venues, has always drawn a diverse weekend crowd and a wide array of wardrobes.

But tonight, the most-prominent fashion statement was the uniform -- as in the police uniform. On foot, horse and bicycle, more than 50 State Police and Philadelphia Police officers -- including Commissioner Charles H. Ramsey, were on hand in an effort to avert a repeat of the May 30 debacle.

And a week after one of Philadelphia's most popular venues was rocked by mayhem and violence, South Street tonight was about as tranquil as the splendid June weather.

Last Saturday night, as many as 10,000 youths, evidently lured by social-networking sites, descended on South Street, overwhelming surprised police officers.

A cabdriver was carjacked and two other people were pulled from their cars and assaulted.

At a police staging area at South and Passyunk Avenue, Lt. Gerry McShea declined to say precisely how many officers were on the street tonight but did say it was "significantly greater" than the standard Saturday night presence.

On a warm, clear and moonlit night, the crowds are about average for a Saturday, the only noticeable difference being fewer families with younger children in tow.

Police promised they would stictly enforce a midnight curfew for juveniles. Police said they believe that the region's teenagers were using social-networking sites, such as MySpace to arrange huge gatherings.

Large numbers of youths have congregated at other times this year in University City and Upper Darby. However, they were not on a scale with the throngs that showed up on South Street last week.

The dense South Street corridor from Second to Ninth Streets, has a rich and sometimes troubled history.

It has long been one of the city's most alluring strips with its mix of idiosyncratic businesses, restaurants and urban panache. While it has undergone many personality changes over the last 40 years, and arguably lost some of that edginess, it remains perhaps the most popular weekend destination in Center City, particularly among young people.

What happened last week was the most-disruptive incident on the strip in eight years.

About 40,000 people showed on South Street for Mardi Gras on Feb. 27, 2001. By nightfall, fighting had broken out, bottles had been thrown and stores looted. In the end, 81 people had been arrested.

Several youths were arrested for curfew violations but none for the violent incidents.

"There was no way we could have anticipated what occurred," Deputy Commissioner Kevin Bethel said Thursday during a community meeting.

That's understandable, Keith Ahn, manager of lulu.ish, a trendy clothing and jewelry store, said this evening. "It's so crowded at night, there's not always much that they can do," he said.

Contact staff writer Anthony R. Wood at 215-854-2443 or twood@phillynews.com