Version 3.6 introduced GeoPackage as the standard format, though Shapefiles and RDS remain available. To help you get the right files, Download GADM data

Top-level subdivisions (States, Provinces, Regions, Governorates).

Geospatial datasets regularly shift as political boundaries evolve. Version 3.6 represents a highly stable snapshot of global administrative frameworks.

If you are starting a brand-new project, consider if you need the absolute latest boundaries found in Version 4.1 , or if the specific historical boundaries of 3.6 are required for your study. Download GADM data (version 3.6)

If you are looking for more up-to-date boundary changes (post-2020), consider checking the latest GADM version, but for robust, historically consistent research, version 3.6 is an excellent choice. Pro-Tip Checklist for GADM Data

# Manual download method download.file("https://biogeo.ucdavis.edu/data/gadm3.6/Rsp/gadm36_USA_1_sp.rds", "gadm36_USA_1_sp.rds") usa_adm1 <- readRDS("gadm36_USA_1_sp.rds")

Right-click the loaded layer, select Filter... , and build an expression (e.g., "NAME_1" = 'California' ). Click OK to isolate your study area. 2. Working in ArcGIS Pro

Once you have downloaded the GADM 3.6 shapefile, you can integrate it into your projects. 1. Loading in QGIS/ArcGIS Extract the downloaded zip folder. Open your GIS software. Drag and drop the .shp file into the mapping canvas.

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