course: Geospatial Mapping with D3 | Pluralsight
mbostock/topojson: An extension to GeoJSON that encodes topology.
mbostock/us-atlas: Roll your own TopoJSON from the National Atlas and U.S. Census Bureau.
GDAL: GDAL - Geospatial Data Abstraction Library
TIGER Products - Geography - U.S. Census Bureau
TIGER = Topologically Integrated Geographic Encoding and Referencing
TIGER products are spatial extracts from the Census Bureau's MAF/TIGER database, containing features such as roads, railroads, rivers, as well as legal and statistical geographic areas.
Cartographic Boundary Shapefiles - Counties - Geography - U.S. Census Bureau
Downloads | Natural