how iowa’s county highways are laid out

[Naked.Driver]

i've noticed that some of you have been a bit confused by the way iowa designates its county roads.
i m o, iowa has one of the most logical county-highway numbering plans of any of the states!
see iowa county highways for the complete grid pattern.
so, if you look at the county-highway letters, you know about where in the state you are. in most other states, i've been on county highways, they appear to be numbered completely at random.
i won't say that all iowa county roads are nice to drive on unless you just want to see them. most are boring little highways that seem to meander more than necessary, but it's fun (i m o) to collect at least one of each letter.
enjoy iowa's highways!

[hotdogPi]

Many of Florida's county roads also have reasonable numbers – they fit in with the state grid.

[DandyDan]

One thing Iowa's system does is it allows the same designation to cross county lines. Minnesota, in comparison, almost always has county road designations change at the county line. And it's better than Nebraska, which has nothing at all.

[Brandon]

One thing Iowa's system does is it allows the same designation to cross county lines. Minnesota, in comparison, almost always has county road designations change at the county line. And it's better than Nebraska, which has nothing at all.

However, in Wisconsin, no one can mix up county highways with state/US/interstate highways.  "Take Highway B to Highway 12 to Highway 90-94".

[hotdogPi]

One thing Iowa's system does is it allows the same designation to cross county lines. Minnesota, in comparison, almost always has county road designations change at the county line. And it's better than Nebraska, which has nothing at all.

However, in Wisconsin, no one can mix up county highways with state/US/interstate highways.  "Take Highway B to Highway 12 to Highway 90-94".

AD and 80 sound similar.

[Jardine]

I took high school drivers ed in '74 in Iowa, and absolutely do not recall a single mention of the grid system.  Granted I may have forgotten, but I dare say not one person in 100 knows anything about the system at all.

I've never figure it out. Can't say I've ever met anyone who knew either.  Figured they were all random.  It is nice the designations do cross county lines.

[index]

Many of Florida's county roads also have reasonable numbers – they fit in with the state grid.

Part of the reason for this is that, often times, when FDOT decommissions a state route, they'll hand it down to the county. I don't know how often this practice is done or if it's been done recently, but I do know there are plenty county routes in FL like this. Typically the existing state route shield will be remarked to say C-XXX.

[NE2]

Part of the reason for this is that, often times, when FDOT decommissions a state route, they'll hand it down to the county. I don't know how often this practice is done or if it's been done recently, but I do know there are plenty county routes in FL like this. Typically the existing state route shield will be remarked to say C-XXX.

If it was a secondary state road (S-x) it was redone as C-x with a small COUNTY overlay. If it was a primary state road (just a number in a shield) the state simply added the COUNTY and optionally a C to the left of the number. Since secondary state roads have not existed since the 80s, any state road shields with C-x are ancient or county jobs.

A remnant secondary state road shield:


A secondary state road given to the county:


A primary state road given to the county:


A former primary state road with a 'C' added:

[WhitePoleRD]

I took high school drivers ed in '74 in Iowa, and absolutely do not recall a single mention of the grid system.  Granted I may have forgotten, but I dare say not one person in 100 knows anything about the system at all.

I've never figure it out. Can't say I've ever met anyone who knew either.  Figured they were all random.  It is nice the designations do cross county lines.

The grid system may not have been around in 1974. I know when I've been in super rural parts of Iowa there are old county road signs still around that would be single letters a la Wisconsin or Missouri.

[kphoger]

I took high school drivers ed in '74 in Iowa, and absolutely do not recall a single mention of the grid system.  Granted I may have forgotten, but I dare say not one person in 100 knows anything about the system at all.

I've never figure it out. Can't say I've ever met anyone who knew either.  Figured they were all random.  It is nice the designations do cross county lines.

The grid system may not have been around in 1974. I know when I've been in super rural parts of Iowa there are old county road signs still around that would be single letters a la Wisconsin or Missouri.

According to Jeff Morrison, the change happened in 1969.

[mgk920]

One thing Iowa's system does is it allows the same designation to cross county lines. Minnesota, in comparison, almost always has county road designations change at the county line. And it's better than Nebraska, which has nothing at all.

However, in Wisconsin, no one can mix up county highways with state/US/interstate highways.  "Take Highway B to Highway 12 to Highway 90-94".

And there are many instances where the highways retain their letters when they cross county lines, too.

Mike

[dvferyance]

One thing Iowa's system does is it allows the same designation to cross county lines. Minnesota, in comparison, almost always has county road designations change at the county line. And it's better than Nebraska, which has nothing at all.

However, in Wisconsin, no one can mix up county highways with state/US/interstate highways.  "Take Highway B to Highway 12 to Highway 90-94".

And there are many instances where the highways retain their letters when they cross county lines, too.

Mike

It's pretty much a mixed bag on that one. H is the same in Racine and Kenosha. As is P in Waukesha and Dodge. However Jefferson county B because BB when it enters Dane and Waukesha County ZZ becomes H when it enters Jefferson.

[paulthemapguy]

This is a bit of an aside, but Illinois seems to have developed a similar grid system just like Iowa's for their county highways--there's just only a few counties in Illinois that use it. (Lake, McHenry, Boone, Grundy, St. Clair, and Peoria.  Possibly a few others.)  The labels for county highways are all alphanumeric, just like Iowa.  East-west highways are A thru around L with A in the north and later letters as you go south; north-south highways are from about M or so through W, with the latest letters in the east.  Lake County is in the northeast corner of the state, and all the county designations start with A and W.