The 26th Amendment was the amendment to the Constitution that took the least time to be ratified. No other amendment was ratified as quickly as this one was. The amendment was first proposed in Congress on March 23, 1971. The amendment was then officially ratified on July 1 of that same year. That means that it took only 107 days, less than four months, for the amendment to go from being proposed to being ratified.
This amendment has to do with qualifications for voting. Before the amendment passed, a person had to be 21 or older to vote in the United States. This amendment lowered the age. It set the voting age at 18. No person could, once the amendment was ratified, be denied the vote on account of their age as long as they were 18 years of age or older.