By Laila Kearney
NEW YORK (Reuters) - More than a million people are expected to crowd into New York City's Times Square under heavy security on Thursday to celebrate the arrival of 2016 with the traditional dropping of the New Year's Eve crystal ball.
Throngs of people were already streaming into the area early in the day, preparing to spend hours outdoors before the official festivities begin with the lighting of the ball at 6 p.m. EST.
Unlike many years, the weather was relatively comfortable, with cloudy skies and temperatures expected to be well above freezing at midnight.
With memories of the deadly attacks in Paris and San Bernardino, California, still fresh, police took extraordinary measures to assure security at an event that has come to define the New York experience for many visitors to the United States' largest city.
About 6,000 uniformed police officers, 500 more than last year, and undercover officers are expected to patrol the area with bomb-sniffing dogs and radiation detectors.
"This is the center of the world on New Year's Eve," said Rick Milley, 60, who traveled from Boston with his wife, Debbie, 59, to ring in the new year in Times Square.
"This was on our bucket list," Debbie Milley said as the couple took pictures of themselves using a selfie stick.
The pair have spent the holiday in New York before but never in Times Square, the Midtown Manhattan crossroads that is a year-round tourist draw, filled with chain stores, family restaurants and flashy advertising displays.
In the hours before the ball drops from the top of a narrow wedge of a building at the southern end of the square, revelers will be entertained by musicians such as Carrie Underwood and Jessie J performing on multiple stages set up in the area.
In addition, more than 100 million Americans and 1 billion people worldwide were expected to watch the festivities on television.
Before entering Times Square, visitors will have to pass through tight security checkpoints. Once inside the square, spectators were to be funneled by police into one of the dozens of viewing pens where law enforcement officers can closely monitor and control the crowd.
The city for the first time will use its new Critical Response Command counterterrorism unit, which includes more heavily armed officers, to patrol Times Square. The unit is trained to detect and respond to attack plots.
Backpacks and large bags have been barred from the area. All other bags will be searched, and metal detectors will be used to screen everyone in the crowd.
Once attendees pass through police checks, they cannot leave their viewing area without going through the security process again.
The famous New Year's Eve ball, which is 12 feet (3.66 meters) in diameter and weighs nearly 6 tons, descends from the top of One Times Square starting at exactly 11:59 p.m. EST.
(Editing by Frank McGurty and Jonathan Oatis)