Three franchises have played in every NBA season. Which?
The three franchises that have played in every NBA season are the Knicks, Boston Celtics, and Golden State Warriors (who began as the Philadelphia Warriors)._x000D_
When are the Knicks, Celtics, and Warriors facing each other in 2021?
_x000D_The three historic teams will face each other across three televised games during five days in December 2021: Warriors at Knicks will play on Tuesday, Dec. 14 (7:30 p.m. ET, TNT); Warriors at Celtics on Friday, Dec. 17 (7:30 p.m. ET, ESPN); and Knicks at Celtics on Saturday, Dec. 18 (8:30 p.m. ET, NBA TV).