It's very hard to make change nationally when it comes to public policy. Typically, if it happens, it happens because of a grass roots effort that picks up steam and the attenion of the media, politicians and big-name activitists.
However, in your local community, making change happen might appear to be easier because of the easier access you might have to councilors, the mayor, etc. Then again, politics is politics (regardless of all politics being local, as Tip used to say).
With the help of social media, however, everyone has a voice and I used mine a couple weeks ago when someone smashed into my parked car and drove away (if you need to catch up, read this).
Last week, I spoke to the Revere Journal about the traffic issue on my street, specifically how social media propelled my personal issue on to the docket of the mayor, a couple city councilors and the traffic committee.
Here's a link to the PDF, page 5 (opens pdf).
My message to you: if you have an issue in your city or town, use the tools are your disposal to make your voice heard. The power is a few clicks away.