Neat idea Machka, I actually just made a list of the states I've bicycled in the other day, thinking that I should try to hit them all. I've visited 48 states, but I must have been wasting my time since I've only biked in 11 of them.
Japan: Kumamoto
Canada: Alberta
USA: Florida, Maryland*, Michigan, Montana, New Jersey*, New York, North Dakota, Oregon, Pennsylvania*, Virginia, Washington, Washington, D.C.*
* = I have cycled across the state, although not necessarily at the longest point.