Three kinds of geography, one of them drawable — A dataset can carry point coordinates, region codes like a borough or community board, or a street address. Only the first can be drawn directly — region codes need boundary shapes and addresses need a geocoder, so both are detected and reported but not plotted.

Coverage, honestly — Of 2,396 datasets, 998 carry some geography and 496 are directly mappable. An empty map usually means the dataset is one of the other 1,900, not that nothing happened there.

Three layers, deliberately — A point map is an all-pairs colour problem: any two datasets' markers can end up adjacent. Past three layers the palette stops clearing the colour-blind separation floor, so the limit is a real constraint rather than an arbitrary cap.