I've been trying to build a full USA map for the Garmin Nuvi. Due to the ever increasing size of OSM data, it's been a challenge to get it to fit on older Garmin units. The only way to reduce map sizes is to omit data.

Here is an experimental Full USA Garmin map using OpenStreetMap data. It is based off of OpenMapChest but looks completely different due to the sacrifices made to get the entire USA (Continental USA plus Alaska and Hawaii) to fit in 4GiB. It does so by further simplifying things and omitting a lot of stuff:

• parking lot and building silhouettes (note: addresses of which were also deleted)
• suburb, landuse (e.g. commercial, industrial, residential) and natural area delineations
• some short driveways and service roads were removed
• grass, trees, park areas
• Bus stop, picnic tables, vacant shop POIs deleted
• Electrical grid deleted
• Piers over water removed
• Short and intermittent (unnamed) streams, some small ponds and all marshes/swamps are gone
• Golfing features and Leisure areas like pools and tennis courts in private property, residential areas, and schools removed
• Physical road blockage icons, which may be added back
• TIGER addresses not incorporated
• Some unnamed foot paths have been deleted
• Pedestrian areas gone, sort of
• No longer mark rocky surfaces and cliffs
• Benches gone

Features that would like to be added back, size permitting... but looks very bleak:
TIGER addresses, Parks, farmland, and natural protected area landuse

I currently can test these maps on my Nuvis: I own a Nuvi 200, Nuvi 200W, Nuvi 255, and a Nuvi 255W. I have not tried to see what I can do with Basecamp and my Garmin Rino.

The main focus for this map was for automotive use - navigation and determining ones location. It still includes bicycle and pedestrian paths, though these are slated for the chopping block if I can't find other ways to keep sizes down. Do keep in mind that 4GiB of gmapsupp.img data will compress below 3GiB as it tends to compress 25% or so. However you cannot use zip files directly on the Garmin.

4GiB is the file size limit of a FAT32 formatted filesystem, which the Garmin uses on its Secure Digital (SD) cards. Note that most likely you will need an 8GB, 16GB, or 32GB SD or microSD card regardless, as "4GB" cards are "marketing" or decimal 4GB and you get less than 4GiB. Don't try to use 64GB or larger cards unless you know they are compatible - 64GB cards are formatted exFAT, which the old Garmins do not understand. Unless your Garmin was made after 2013 or so, it probably does not support exFAT. This is most unfortunate as exFAT gets rid of the 4GiB limit.

Vanade-OSM-USA-2024-03-06T212054Z.zip.torrent 30286 bytes, Zip file download size: 2999.3 MiB, gmapsupp.img size is 4226.4 MB.
Vanade-OSM-USA-2024-03-21T130000Z.zip.torrent 30186 bytes, Zip file download size: 2988.7 MiB, gmapsupp.img size is 4210.6 MB.

Removal ideas for future size reduction:

In September 2022, I found a bug in my pruning and was able to recover a substantial amount of space, and should be able to hold off impending doom for probably at least 2024. The seemingly largest source of new data is the massive addition of new points - whether from new ways or POIs being added.

You'll need to use a bittorrent client to download, an unzip program to decompress the archive, and then copy the resultant gmapsupp.img into \Garmin\gmapsupp.img of an SD card to use this. Make sure you also select the map using the menus on your device.

And the typical disclaimer, I am not responsible for people driving their cars off a cliff, into barriers, getting lost after your GPS crashes, or other problems due to any errors on the map.

Apologies for the slow seeding. I do not have high uplink bandwidth and will stop seeding older maps when I clean up the semi-automatically generated mess. While in experimental mode I'm currently trying to build maps with a fairly quick cadence, but this is not healthy for the bandwidth limits I have: the longer the time between releases means people can help seed files longer, but the data is obsoleted by new data. Currently I build every few days or whenever I want to see my changes added. I do not archive old versions.

The maps provided here are provided free of charge, free to distribute, but are subject to copyright by the OpenStreetMap Contributors. I also contribute to drawing, updating, cleanup, and adding POIs into OSM data, my changeset count is over 7000 in early 2023.

I try to use proper SI standards for abbreviations.
1MB=1,000,000 bytes
1MiB=1,048,576 bytes (4.8% larger than 1MB)
1GB=1,000,000,000 bytes
1GiB=1,073,741,824 bytes (7.4% larger than 1GB)

4GiB = 4096MiB = 4194304KiB = 4294967296 Bytes
4000MiB = 4194MB
4000MB = 3814MiB