On the Southside of Capitol Hill clicking on a sign takes you to a web page where you can register to vote if you are a U.S. citizen.

You can also check out U.S. Presidential Candidate info areas in SL (run by individuals not by actual campaigns from what I can tell) and get a landmark from which you can teleport to these candidate info areas.

You can also contact Senators and Reps through another board there on the South Capitol steps that links to website access to a database on districts throughout the United States.
This is going to be an interesting next 17 months as the U.S. Presidential election comes to SL in a big way for the first time.