Currently a huge work in progress, could take months (since I’m alone) and the map would crash a lot due to GTA:V’s silly limits. I’ve gotten some progress extracting the map due to a zenhax tool that made it possible. (Credits to daemon) Imagine adventuring the whole United States in a FiveM server? 
Please, don’t sue me or send me a C&D, Ubisoft. 
Using XNALaramesh’s blender plugin, I was able to import these Crew 2 exported/extracted ASCII files/models into Blender and export them as .xml’s using Sollumz plugin. By the way, certain cities can be ripped from the game itself. According to daemon, The whole USA map is split into 20x12 areas (0,0 is south west corner). For the first game, its 19x11 areas. Each area is square 8x8 sectors. I need a lot of help with this project in finding sector areas and coordinate areas. I don’t seem to have enough free time on my hands. Here are some trees/vegetation successfully exported from The Crew 2. After this project is finished, I’ll make it a map resource on GTA5-mods and make it FiveM ready as well. Minimap might be a little tricky, maybe even impossible.
To support me or see the progress of this project in the upcoming months, visit my Discord.