Which legislation was responsible for changing the voting age in the united states?

The 26th amendment to the U. S. constitution changed the voting age. This amendment was approved the U. S. congress on March 23, 1971. A significant contextual element at the time was the Vietnam War. Soldiers were being drafted to go to war (selected by lottery), but could not legally vote at the time. This idea contributed to the idea of lowering the voting age from 21 to 18.

the answer is the 26th Amendment