Electronic M wrote: "I don't think I have ever seen an unmarked cross roads on any public road here in the US..."
There's actually (at least) one in the sprawling metropolis of Columbus, Ohio. A T-intersection, not a true crossroads, though. The intersection of Millennium Court and Citygate Drive (both real, named streets, not driveways) has no stop sign, yield sign, or anything. Ohio law dictates a stop (sign or not) when going from a lesser to greater street, based on memory from... umm... let's say 40+ years ago. But I think it's interesting since it's near a post office and definitely not an unused road.
Streetview here:
https://www.google.com/maps/@40.0173...4!8i8192?hl=en