This post documents interesting sources for world-level, country-level, and sub-national level (i.e., states/provinces, cities, counties, etc) maps (administrative areas) data. It could be particularly useful when you are trying to downscale gridded data to specific geographical levels in spatial analysis.

Database of Global Administrative Areas (GADM)

GADM provides maps and spatial data for all countries and their sub-divisions. You can browse the maps or download the data to make your own maps.

See an example of spatial data for China. Level-0, 1, 2, 3 stands for country level, province level, city level, and county level I guess. But you should double check that.

See the data package for more information in data format.

• Reference

  Dang and Trinh. Does the COVID-19 lockdown improve global air quality? New cross-national evidence on its unintended consequences. Journal of Environmental Economics and Management 105 (2021). Link

Natural Earth

Natural Earth is a public domain map dataset available at 1:10m, 1:50m, and 1:110 million scales. Featuring tightly integrated vector and raster data, with Natural Earth you can make a variety of visually pleasing, well-crafted maps with cartography or GIS software.

This dataset provides vector data at country-level, state-level, and populated places and obviously, is not as detailed as in GADM. But it pretty suitable for ploting at the the worldwide level. Natural Earth also provides vector data on coasline, land, ocean, reefs, rivers, lakes, etc, as well as raster data.

• Reference

  Hong, C., Burney, J.A., Pongratz, J. et al. Global and regional drivers of land-use emissions in 1961–2017. Nature 589, 554–561 (2021). Link.