Voronoi diagram of local high schools

How might we divide the county so each student goes to the school closest to them? How might we do this only using compass and straightedge? Click "Show Voronoi cells" to see one option for districting. The "New School" can be dragged around the county.
"Actual Feeder Map" from albemarle.org, accessed 4/10/14 "Overlay Map" from Google Maps, accessed 4/10/14 Locations of schools from Google Maps Engine Lite, accessed 4/10/14 You gotta check this out too.