The history of voting in the US takes a lot of twists and turns and at different points in time discriminated against lots of different people.
This only lightly covers the subject, but at the time of the Constitution only 10-15% of people were allowed to vote. And another thing it doesn't discuss is secret ballots. Secret ballots were a big deal if you live in a town with one employer and that employers nephew is running for office. If everyone knew how you voted this obviously could effect you long term.
So your vote was hard earned over the course of centuries. Don't take it for granted, your ancestors fought hard for it.
Sans Peur Ne Obliviscaris