As I mentioned before after release of open beta for 1.58 we have about 4% of undiscovered roads – on my side it was 96,29% opened just after the update. It is the result of massive Rout 66 Rework and other map enhancements. But SCS not only did this beautiful rework but also added new easter eggs and hidden roads, so count of markable but secret roads is growing. below you can see couple videos with hidden paths in Arizona and Nevada.

And overall 1.58 changes and Route 66 teasers