There are also dedicated offline map apps you can use. My current one is OSMAND that works off Open Street Map data and can do turn by turn directions without a

There are also dedicated offline map apps you can use. My current one is OSMAND that works off Open Street Map data and can do turn by turn directions without a cell connection. It's a couple gigabytes to have a complete map of the US that's at least up to date enough to navigate out of the back country.