how did each group win the right to vote (blacks, women, 18-21 year olds)
BLACKS- Civil war, most could vote in the north, in the south the right to vote was established by the 15th amend.
WOMEN-1919,1920 with the 19th amend.
18-21 YEARS OLD- 1971, Vietnam war, 26TH amend was ratified, lowered the age from 21 to 18. Bc the demands from groups that had been deprived the right to vote, if they were going to war.