Americans celebrated Thanksgiving on Thursday with heightened security measures in place and tensions running high over the conflict between Israel and Hamas in Gaza, potentially casting a shadow over a normally joyous holiday.

War in the Middle East has prompted officials to take extra precautions at airports and shopping malls across the United States and along the route of New York’s signature Macy’s Thanksgiving Day Parade.

A quintessential American rite, Thanksgiving brings together family and friends for turkey dinner and watching the parade and American football on TV. It also marks the most intense week of the year for travel and start of the holiday shopping season on Black Friday, the day after Thanksgiving. Both are seen as indicators for the health of the economy.

But this year the holiday takes place against the backdrop of a war that has provoked a surge in antisemitism and Islamophobia in the United States. The FBI has warned Congress that the threat of terrorist attacks are at the highest in nearly a decade.

Reflecting the anxiety, a fiery car crash on a US-Canadian border bridge set off alarm bells on Wednesday before officials announced there was no connection to terrorism. President Joe Biden urged national unity and “decency” in a phone call with NBC television during coverage of Thursday’s parade.

“Today is about coming together,” Biden said. “We can have different political views but … we should focus on dealing with our problems. … And stop the rancour.”

New York Mayor Eric Adams, when asked about protests that may unfold during the parade, told reporters the city respected free-speech rights but would not tolerate any disruption.

“You’re not going to destroy property, you’re not going to injure people,” Adams said on Wednesday.

New York police said they were unaware of any specific or credible threats.

Thanksgiving Day as an official holiday dates to 1863, in the middle of the American Civil War, when President Abraham Lincoln proclaimed the last Thursday of November as a day to give thanks and seek healing.

US schoolchildren learn that the holiday roots trace back to the Pilgrims, who settled in modern-day Massachusetts at Plymouth Rock.

In 1620 the newcomers celebrated the autumn harvest with the native Wampanoag people. For many Native Americans, however, Thanksgiving is a day of dark reflection about the genocide that followed.

• A Reuters report