Revive Civics in US High Schools. Actually TEACH our young adults how our government was formed, how it works, and MOST importantly - their role in that Government. If more citizens were educated properly about our democratic Republic as children and teens, then as voting age adults we might see more of them voting.
We truly have a plutocracy in practice instead of a democracy. It would be great to have elementary students to begin to study civil responsibilities, particularly voting, when they are young. Education is one of the key factors for people voting. If children begin to study the serious responsibilities of voting, they will get a better education, teach their parents, and hopefully exercise the right to vote as adults.