I actually wasn't too bad at this
I found a sign in round one which said Ontario so that made it easy, the rest I just went based on the language I saw in road signs or on buildings. I'm proud of Round 4 (D on the map) though as I was on a highway with nothing for miles but there were oil derricks so I guessed Texas and picked the longest road I could see :p
[edit] I guess the link doesn't show your results after a while I was fairly close with all of them, a few hundred km away at most.