Hello again dear map & Garmin-hackers, I've also built a routable 3.5GB gmapsupp.img for my nuvi 200's SD card and been able to route a long drive that ends deep into the new map. Because the map was larger than my 32-bit Java could handle, I joined using GMapTool http://www.gmaptool.eu/en/content/merging-maps That tool doesn't create any address index though. Can mkgmap do that step? I tried this command line, and it did write a new routable 3.5GB map image from the supplied one, but the nuvi still isn't searching for addresses in it: java -Xmx1650m -jar mkgmap.jar --gmapsupp "--style-file=d:/Garmin maps/mkgmap-r3692/examples/styles/default" --precomp-sea=i:\maps-new_style\sea_20161017.zip --generate-sea --index --bounds=i:\maps-new_style\bounds_20161017.zip --location-autofill=is_in,nearest --x-split-name-index --housenumbers --add-pois-to-areas --remove-ovm-work-files --output-dir=i:\ "D:\Garmin maps\Mex-W-US-Can.img" (I have tried again with a tiny map of two local tiles joined, but my nuvi does not recognize this 17MB gmapsupp.img as a map! Odd that the 3.5GB map mostly works when moved in its place, I think I built them both the same way... since that is a joining experiment with GMapTool and not mkgmap, it's for entertainment only. Am more interested in learning how to add the index) -y