At what 1963 drag racing event did the Christmas Tree starting system debut?

The Christmas Tree starting system debuted at the 1963 U.S. Nationals in Indianapolis.

Chrondek introduced the system at the NHRA U.S. Nationals, where it replaced less precise starting methods with a visible sequence of lights. The device was developed with help from Lew Bond, a Dragtronics owner and NHRA Division 1 director. Its purpose was to make starts more consistent and easier for drivers and officials to judge.

The original 1963 Tree used five amber lights but did not yet have the separate pre-stage and stage bulbs familiar today. Those staging lights were added at the 1964 Winternationals in California and were gradually incorporated into the Tree itself.

The system changed again over time. In 1971, NHRA introduced a Professional Tree that illuminated only the final amber bulb before green for professional classes. The modern Tree therefore differs substantially from the original, but the 1963 U.S. Nationals remain its recognized debut event.