Please go to this location and download all of the .img files corresponding to places you may wish to travel to. At the present time, all regions of the United States are available for download, as well as entire country maps for Canada and Mexico.
After downloading, copy all the .img files to a directory called "Map" on a MicroSD card, put said MicroSD card in your Garmin GPS, change the settings to disable any older built-in maps of the US your device may have come with, and you should be good to go.
My maps for the United States are vastly superior to OSM-based Garmin maps that you may find available for download from other sources. In addition to compiling the OpenStreetMap data, I have included street address information from the US Census Bureau's TIGER data set. This makes street address lookup work much better than with OSM-based maps from other sources.
To make street address lookup work even better, I am now integrating data from OpenAddresses into my maps. The US South region map already includes this data, and OpenAddresses-integrated maps for other regions are coming soon.
At the present time, my maps for Canada and Mexico are simple compilations of the OpenStreetMap data. They are, therefore, no better than what you would get from downloading the same maps from other sources. However, I make them available anyway so that I can be a one-stop shop for all of your North American mapping needs!
If you need maps for regions outside of North America, I recommend OpenMapChest.
Similar to my maps for Garmin devices, I have made OsmAnd maps which integrate data from both OpenAddresses and TIGER, meaning they will have vastly superior street address lookup compared to what is available from maps from other sources, including especially the maps available from the OsmAnd project itself. These maps are available here. I had to split Texas into two maps, one for East Texas and one for West Texas. The East/West dividing line runs about midway between Dallas and Fort Worth.
The reason that I had to split Texas into two maps, even though I am able to distribute Garmin maps for entire regions of the US, is due to limitations in the OsmAnd map format.
I do plan to make high quality maps for other US states in the future. However, if you need maps for other states right now, I recommend this source for those maps. Maps from that source integrate OpenAddresses but not TIGER data.
In addition to my Texas maps, I have also made a modified version of the OsmAnd Android app. It makes the Android Auto screen change from day to night mode based on sunrise/sunset data, rather than based on information from the car. It is available here.
In order to use this APK with Android Auto, you will need to fool Android Auto into believing that you installed it from the Google Play Store. For Android 10 and older, that is fairly easy. Enable Developer Mode on your phone, and do the following from a computer with ADB installed:
adb push osmand_mine.apk /data/local/tmp/
adb shell pm install -i "com.android.vending" -r /data/local/tmp/osmand_mine.apk
For Android 11 and newer, you still need to do the above. However, in addition to doing those steps, you will probably also have to root your phone and then use this tool to fix some metadata which would otherwise identify the app as not actually having been installed from the Play Store.