I want to create interactive historical maps (e.g. world borders in 1914). Obviously I will need shapefiles in geojson/topojson format for borders which do not exist anymore. Even if some of these shapes exist (I have not found any), I will need to create some on my own.
Does anybody know a good platform/tool to create these shapes? So far I have found geojson.io, but it is very difficult to create country borders with this tool since shared border segments can't be reused.
If your aim is to draw historic lines or shapes, best would be to use QGIS, load STRM for the topography as a background for reference, then draw the borders as shp vector lines or polygons. One year (date) as one layer, each layer of the .shp will then give an object in the topojson, itself containing an array of objects (line or polygon).
Shapefile being the format of reference for geographic data, it's a good idea to store your raw data as shp. From there you will always have tools to convert data out.