#D3.js JSON and TopoJSON
To download the .shp files use http://www.gadm.org/download
use ogr2ogr to convert shape files to .json
☺ ogr2ogr -f "GeoJSON" /tmp/world.json ~/Downloads/world_borders.shp world_borders
Use the TopoJSON to reduce the size of these, see https://github.com/mbostock/topojson/
Command to convert to a topojson format, preserving Name and Type and are also simplified with the -s 10e-9 precision threshold for Visvalingam simplification, in steradians setting.
☺ topojson -o public/topo/USA_adm1.json -p NAME_1=country -p TYPE_1 -s 10e-9 /tmp/USA_adm1.json