Answer:
They increased American participation.
Step-by-step explanation:
Before amendment was created, the constitution only allow white male citizens to give their votes. This made other social group cannot participate in the democratic government. Amendments changed this situation for the better.
Amendments such as 15th amendment and 19th amendment increase the participation of other group citizens in United States. The 15th amendment granted black citizens with the right to vote and the 19th amendment granted women with the right to vote.