With three states raising speed limits this year I decided
to make a map of where America stands:
http://www.mit.edu/~jfc/speed/states.gif

The map shows the highest speeds posted in the state; in
the case of Texas I anticipated the posting of 80 MPH speed
limits later this year.

The corresponding map for two lane roads is
http://www.mit.edu/~jfc/speed/states%202L.gif

States with some sort of rumbling about increases in recent
years include Idaho (75 two lane), Kansas (75), Kentucky
(60 two lane, 70 freeway), Oregon (70), Minnesota (60 two
lane and 75 Interstate), and Wisconsin (75 freeway). All
of these states have neighbors with higher speed limits.

I wanted to make a map for four lane roads but I don't think
it would be very informative. In some states rural divided
highways are almost entirely freeways; in others they are
limited access without interchanges; in others they are not
limited access.

States where I know there are non-freeway rural four lane roads
with the maximum speed limit on such roads between two lane
freeway limits are Alabama (65 on four lane roads), Florida
(65 on divided highways), Indiana (60 on divided highways
without access control), Missouri (65 on divided highways
without access control), North Dakota (70 on divided highways),
South Dakota (70 on divided highways), Washington (65 on
divided highways), and West Virginia (65 on limited access
corridor routes). Of the rest, some post expressways like
freeways and others post expressways like two lane roads.
--
John Carr )