USDA Plant Hardiness Zone Map
To download a very large personal version of the hardiness map, visit https://planthardiness.ars.usda.gov/PHZMWeb/Maps.aspx and select the region or nation and the size of the map. You can preview the map, open the full map in your browser, or save the map to your computer. The full US 300dpi map is a jpg file 26.3meg in size.
For more information, you can poke around the USDA National Arboretum. (They seem to have a lot of broken links due to web site changes, as of 9/30/2020).
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