Others chose to stand and hold a fist in the air. Some teams locked arms as they stood on the sideline.
The kneeling from players is an evolved form of what former 49ers quarterback Colin Kaepernick first did in 2016.
On Sunday, he tweeted his take on some of the NFL's social justice initiatives - calling them "propaganda."
He also said the league is still blackballing Eric Reid, Kaepernick's former teammate who joined him in protest four years ago.
Shots of both Kaepernick and Reid are featured in the NFL's video of "Lift Every Voice and Sing" -- largely considered the black national anthem.
The video is being played ahead of games during week one.
One thing noticeably absent this year are fans. Only a couple cities are allowing people inside stadiums due to the coronavirus pandemic.