1. Jury Duty

The only thing which is practically guaranteed to happen from my registering to vote is that I will be drafted for jury duty.

In most places, jury duty is based on voter registration, and since so few people register to vote, there is a good chance you will be drafted within a few months of registering to vote.

I have nothing against serving on a jury, but in the USA, something like 97% of cases are settled before the jury gets to decide anything. It's quite likely that all that will happen is a day wasted at court. Even if you are picked as a jury pool candidate, if you have any strong opinions either way, you will be disqualified. So forget any chance of having a positive impact on the law – the system is stacked against jurors changing the outcome from what the legal system demands. The conviction rate in the USA is about 90%.