I've had to adjust to both metric speed limits (kph, instead of mph), as well as the situation you are describing. I moved to Canada from New York State about 20 years ago, and I find myself still musing about the differences in speed limits, signage, and the ACTUAL speeds that people normally drive.

There are gong to be differences from state to state. But I think Nammu's summed-up what I learned, and lived with, all those centuries ago.

The basic rules of the road don't change very much over time.