Final answer:
Citizens 18 and older gained the right to vote with the passage of the 26th amendment.
Step-by-step explanation:
The group that gained the right to vote with the passage of the 26th amendment was Citizens 18 and older.
The 26th Amendment to the United States Constitution was ratified on July 1, 1971, lowering the voting age from 21 to 18. This was in response to the Vietnam War, where young men aged 18 and older were being drafted and sent to fight in the war but did not have the right to vote for the leaders making decisions affecting their lives.
This amendment extended the right to vote to young citizens who were 18 years old and older, regardless of their race, gender, or any other factor.