The first stage was based on religion and ownership of property. At first, only those of certain religious beliefs could vote but this was abandoned quickly and also only those who owned property could vote but this was abandoned too and a huge number of voters got their suffrage rights as not you could be from any religious background and social class and still vote
The second expansion occurred after the civil war. Following the civil war, the electorate got increased when African-American people were given voting rights. Although racist states found ways to legally disenfranchise them and prevent them from voting, they still had voting rights in theory and those in free states practiced them.
The third expansion was when women were allowed to vote when the 19th amendment was ratified and women were allowed to vote in all states. Before that, women could not vote and now they could which means that the amount of possible votes doubled since there is almost the same number of women as there is of men.
The fourth expansion happened when the civil rights struggle occurred and laws were introduced to prevent disenfranchisement of African-Americans. This brought a lot of voters from southern states where voting was not possible for them in praxis since they had to pass tests or pay fees or similar things to vote
The fifth was later when youth was allowed to vote. It was established that states may not raise the minimum age requirement for voting over the age of 18, meaning that all states had to allow all voters age 18 and up to vote if they wanted to. This brought a lot of young voters since some states made it mandatory to have a minimum of 21 for example.
