Is every American adult allowed to vote?

"When the United States of America began as a country, only white men who owned land could vote. Over the last 230 years, people have fought and protested and even died to expand the right to vote to include every adult over the age of eighteen--in theory. Today, are there ways you can lose your right to vote? And if it's too difficult to vote, can we really say that you still have that right? Voting is the best and sometimes only way Americans can have a say in their government--which is why it's worth fighting for"--OCLC.