Today the Department of State's Humanitarian Information Unit released a new data set, Large Scale International Boundaries, presenting it for the first time at the Tech@State conference. This is the most accurate and complete set of world boundary lines believed to be available. Most lines are accurate to within one kilometer, and no lines are known to exceed four kilometers of inaccuracy.
From the Humanitarian Information Unit's description of the data:
The boundary line depiction research (“recovery” of the authoritative location of the line) has been done over the past decade or so by geographers at the State Department and colleagues from other agencies, and is based on modern imagery, elevation data, relevant maps, treaties, international arbitration and court rulings, and other sources.
The dataset is available immediately as a public layer on TileStream, and will by available on hiu.state.gov early next week. The layer is transparent and can be combined with other layers via the TileStream map builder. Here is is on top of World Blank Bright, a basic land area layer:
The MBTiles map was designed and rendered with TileMill, our open source map design studio. In order to get great looking lines, we preprocessed the data to some extent before rendering. The lines were grouped and merged based on their properties in order to avoid potential rendering oddities, and also to reduce the amount of data in the database without losing any information relevant to the cartography. We also derived simplified geometries for small-scale resolutions.
If you are a TileStream Hosting customer, this layer is available for you to use on your own maps right now via the map builder feature. Anyone is also free to download the MBTiles file for use with our iPad App or other software that supports MBTiles.