Many players took a knee or sat during the anthem, while some entire teams remained in the locker room.
Pete Hegseth spoke to several NFL fans at the New York Jets-Miami Dolphins game to see what they thought these anthem protests.
One woman said it's a "disgrace" and "unethical" for players not to show respect to the country and those who risk their lives to protect it.
She said if players on her favorite team continued to demonstrate during the anthem, she would stop rooting for them.
"It's disgusting," she said.
A man said he agrees with Trump "150%" that NFL owners should fire players who protest during the anthem. He pointed out that if he decided to protest at his job he would "probably get canned."
On Sunday, Trump re-tweeted calls for a fan boycott of NFL games.
"They're paying these guys to do a job. They're not supposed to be involved in politics," another woman said.
One man, however, said players have every right to engage in peaceful protest. He suggested that if Trump wants to weigh in on the NFL, then maybe he should get involved in one of the games and "take a hit and get a concussion."
The Jets' players locked arms during the anthem, but none of the team's players took a knee.