Increased security measures, including sand-laden dump trucks and bomb-sniffing dogs, are being put in place for the annual Macy's Thanksgiving Day Parade in New York City on Thursday, police said.
Last week, an Islamic State (IS) online magazine called the parade "an excellent target" and suggested its readers use motor vehicles to kill and injure people.
IS claimed responsibility for an attack in Nice, France on July 14 — Bastille Day — when an attacker drove a cargo truck into a crowd, killing more than 80 people.
While they have verified no credible threats, the New York City Police Department said it was deploying more than 3,000 officers — both in uniform and plainclothes — along the 4-kilometer (2.5-mile) route through Manhattan. The parade beings at 9 a.m. EST (1400 UTC).
As an added safety measure, more than 80 city sanitation trucks filled with sand were parked Wednesday afternoon at intersections and at strategic spots along the parade route. Parade officials expected nearly 3 million people to line the route.
The use of the trucks was prompted by the Nice attack. Metal barricades also are lining the parade route.
"The Nice attack was an indicator of something we had to make adjustments because of," New York Mayor Bill de Blasio said Tuesday. "That's why the sand trucks are there. And you will not see vehicles crossing the route of the parade."
Railroad travelers and commuters make their way through Union Station in Los Angeles, Nov. 23, 2016. Tens of millions of Americans are taking to the roads, airports and railways for the Thanksgiving holiday.
The New York police have an additional security challenge this year as well: President-elect Donald Trump's high-rise residence is just a block from the parade route. But Trump and his family are spending the holiday in Florida.
Thanksgiving traditions
In the U.S., traditions for Thanksgiving Day include feasting on turkey, watching football on TV performing community service for the less fortunate.
Another tradition is traveling to visit family and friends, with millions of Americans taking to the roads, air and railways Wednesday for what is expected to be the busiest Thanksgiving holiday travel period in almost a decade.
An explosives-detection dog sniffs as passengers go through a security checkpoint at Hartsfield-Jackson Atlanta International Airport ahead of the Thanksgiving holiday in Atlanta, Nov. 23, 2016.
Almost 49 million people were expected to travel 80 kilometers (50 miles) or more between Wednesday and Sunday, the most since 2007. Officials attributed the increase to lower gas prices and an improving economy.
WATCH: Obama Introduces Lucky Turkeys, Tater and Tot
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Obama Introduces Lucky Turkeys, Tator and Tot
WATCH: Obama Pardons his Final Thanksgiving Turkey
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Obama Pardons his Final Thanksgiving Turkey
Also Wednesday, President Barack Obama got the holiday mood started at the White House with the traditional pardoning of the national Thanksgiving turkey. This year, there were two.
"It is my great privilege — well, it's my privilege — actually, let's just say it's my job to grant them clemency this afternoon," Obama said.
Obama gave ceremonial freedom to Tater and Tot in the Rose Garden, flanked by his nephews Aaron, 4, and Austin Robinson, 6, rather than daughters Sasha, 15, and Malia, 18. Obama joked that the girls "couldn't take" his "dad jokes" anymore.
The president did get serious to reflect on the spirit of Thanksgiving. Obama said it's a time to remember that "we have a lot more in common than divides us.'' He also challenged Americans to show the world that the United States is a generous and giving country, and to make sure everyone has something to eat on Thanksgiving.
In Florida, Trump released a video in which he said, "It is my prayer that on this Thanksgiving, we begin to heal our divisions and move forward as one country, strengthened by a shared purpose and very, very common resolve."
Darryl Hamlett embraces his fiancee, Beverly Conners, as he arrives off a bus from New York to spend the Thanksgiving holiday in Atlanta, Nov. 23, 2016.
The origin of the pardoning a turkey tradition is unclear — tales of spared turkeys date to the 19th century and the days of Abraham Lincoln, whose son, the story goes, persuaded him to let one of the majestic birds live.
John F. Kennedy was the first president to formally spare a turkey, just four days before he was assassinated in November 1963, but it wasn't until the administration of Ronald Reagan that pardoning became a White House ritual.
Thanksgiving is celebrated each year on the last Thursday of November. It marks the start of the holiday season in the United States.