Minnesota county road signage - white square vs. blue pentagon - which counties?

[KCRoadFan]

Because of having been up there often to visit relatives, Minnesota is a state I'm very familiar with. One thing that I know from our travels there is that the state has two different signs for county roads: namely, the MUTCD-standard blue pentagon, as well as a white square sign. What I would like to know is: is there a method to the Minnesota madness? For example, what counties tend to use one or the other? Are there clear trends in certain areas of the state? As far as where we've been, there seems to be a lot of variation even within counties; I've sometimes even seen both on the same sign assembly! I believe the metro counties (Hennepin, Ramsey, Dakota) tend to use the pentagon far more often; on the other hand, the rural counties on I-35 in the south (Freeborn, Steele, Rice) seem to prefer the white squares, but there are a few pentagons. Wright and Stearns counties, northwest of the Twin Cities, seem to use the pentagons and squares in roughly equal proportion, from what I can remember.

These are the counties I'm most familiar with because they're the ones we've most often visited, so I can't really speak for other counties. I'm eager to hear from Minnesota users, as well as those who know the "North Star State" well, to fill me in on this topic!

[texaskdog]

I know they used to all be white until the 80s.  I believe the blue ones are "state aid" highways, whereas the white ones are all county funded.  What that means beyond the obvious Froggie or Riner will have to explain more.

[Mdcastle]

The white squares are the old state standard (See also: Wisconsin). Counties are given the choice as to whether or not they want to partially of fully switch to the national standard blue pentagon. Some have fully switched, some have chosen to use a mix with the pentagons corresponding to the more prominent but not necessarily CSAH highways, some are in the process of transitioning, and some are still all white squares. There's been chatter at MnDOT about forcing all counties to fully switch to be MUTCD compliant but nothing official yet.

[TheHighwayMan3561]

I started a thread for some of this stuff a while back, which may help some questions.

https://www.aaroads.com/forum/index.php?topic=24755.msg2405913#msg2405913

[KCRoadFan]

I started a thread for some of this stuff a while back, which may help some questions.

https://www.aaroads.com/forum/index.php?topic=24755.msg2405913#msg2405913

Should we merge this thread with the earlier one?

[TheHighwayMan3561]

I started a thread for some of this stuff a while back, which may help some questions.

https://www.aaroads.com/forum/index.php?topic=24755.msg2405913#msg2405913

Should we merge this thread with the earlier one?

Not up to me, but I don't think it needs to,