[mlunar]

SVG is kind-of terrible for maps, but you can get pretty small with GeoPackage (read: sqlite). I recently spent a bit too long on exactly this problem and ended up with the following.

116KB - 5MB for country borders

16MB - 52MB for ~50K city/county level borders based on geoBoundaries

The range of sizes depends on how much custom compression/simplification you put into it. The source files are about 10x bigger, but that's already pretty small.

Topojson might be even smaller though.

Check the repo for details /selfplug https://github.com/SmilyOrg/tinygpkg-data

[keepamovin]

Thank you we forked your repo! What makes you say SVG is kind-of terrible for maps?

[mlunar]

Thanks!

Well, mostly that it's text / XML you usually have to parse in full and boundaries are data heavy, so if you have anything more than a world map, I don't see that working very well.

In contrast with the OP or GeoPackage, you can query by tiles/range and only extract the boundaries you need if you're zoomed in somewhere. If you use Tiny Well-Known Binary compression, you can also shrink the data quite a bit while keeping the querying capabilities.

But if you only ever need to render the whole thing, topojson is probably the winner as it cleverly encodes only unique borders once, so it tends to be a lot smaller.

And of course if SVG works for your case, go ahead and use it, it's surely the easiest way to render vector gfx in the browser :)