Shapefiles at census.gov download as .zip files unzip to .shp convert to geojson as .json files import to MongoDB as Shapes with proper coordinates. Shapefile.find(id).to_json => geojson geospatially index the files and perform the following searches:

shapes and places near a point polygons that apply to a point

For the project, I'm using nofxx-georuby gem

MongoDB some custom ruby code that I'm using to plumb this through

To create a geospatial index with mongo, if :coordinates is an array of [lat,lng] arrays, it can be indexed as coordinates : "2d".