Most sign permit technicians assume the local government whose name is on the map is the one whose code governs. Usually that’s true. But our database tracks a specific verdict — NO_AUTHORITY_cascades_to_county — for governments that never adopted independent sign-code authority at all, which means the town on the map is not the government you actually need to call. Nationally there are 1,272 governments carrying this verdict. Almost all of them are in two states.
Illinois and South Dakota are almost the entire national total
| State | Cascade-to-county governments | Share of national total |
|---|---|---|
| Illinois | 637 | 50.1% |
| South Dakota | 514 | 40.4% |
| Missouri | 121 | 9.5% |
Illinois and South Dakota together account for 90.5% of every cascade-to- county government we track nationwide. Add Missouri’s 121 and the three states combined make up the entire national total of 1,272 — there is essentially no cascade-to- county pattern of any real size outside these three states in our current data.
And it’s not spread evenly within those states either
Within Illinois, every single one of the 637 cascade cases is a township-type government. Within South Dakota, the same is true of all 514 cases. This isn’t a mix of small cities and townships that happen to have skipped sign-code adoption — it is specifically the township layer of government, in exactly these two states, that overwhelmingly never adopted its own sign authority and instead defers to the county.
That tracks with how township government works in both states: Illinois and South Dakota both have a large number of townships that function as minimal administrative units — often handling roads and a handful of other services — without the planning and zoning apparatus that would typically produce a standalone sign code. Sign authority, in the absence of a township adopting it, sits with the county by default.
Why the population number stays small even though the government count doesn’t
The combined population across all 1,272 cascade-to-county governments nationwide is 863,521 — a small number relative to how many governments carry the verdict, which is exactly what you’d expect from a pattern concentrated in small rural townships rather than population centers. This is a case where the government count (1,272, or 3.8% of all governments we track) meaningfully overstates how many people the pattern touches, and the population figure (roughly 0.2% of the population we track, covered in more detail in who holds sign authority in America) undersells how often a technician working in these two states will actually run into it. If your work regularly takes you into Illinois or South Dakota townships, this pattern isn’t a rare edge case — it’s close to the default.
It is also worth separating this verdict from the two that look similar. A cascade means the township could have adopted sign authority and did not, so the county code governs. That is different from a county that never adopted a sign code at all — in which case there may be no local code to read — and different again from a county that is legally barred from regulating signs, which is the subject of the states where counties can’t regulate signs. Three verdicts, three different next steps, and only one of them ends with “read the county ordinance.”
What this means on the ground
If a project sits in an Illinois or South Dakota township, do not assume the township office is the right call before you check. The practical sequence is:
- Confirm whether the township itself has adopted an independent sign code. In Illinois and South Dakota specifically, the base rate says it probably has not.
- If it hasn’t, the county’s sign code governs the property instead — including the county’s permit process, fee schedule, and enforcement.
- Confirm this before quoting the job, not after a rejected application. A township office that doesn’t administer sign permits will often say so quickly if asked directly, but a generic call asking “what are your sign rules” can get answered by whoever picks up the phone, correctly or not.
Missouri’s 121 cases follow a related but not identical pattern and are worth the same verification step if your work touches Missouri townships, even though the concentration there is less extreme than in Illinois or South Dakota.
Why this isn’t just “townships are weak governments”
It would be easy to conclude from this data that townships in general don’t hold sign authority, and that’s the wrong takeaway. Illinois and South Dakota, plus Missouri, account for the entire national total of 1,272 cascade-to-county governments — which means every other state with a significant township layer of government, including states in the Midwest and Northeast with large numbers of townships, is not producing cascade cases in our data at any meaningful volume. Whether a township holds independent sign authority is not a property of “township” as a government type; it is a property of the specific state enabling statute that created that township and decided what powers it was handed. Illinois and South Dakota happen to be two states where that statute, for most townships, did not include independent sign-code authority. That is a state-law fact, not a township-government fact, and it is exactly why we track the verdict at the individual government level rather than assuming it from government type alone.
For a technician working across state lines, that distinction is the practical warning: the assumption you build up working townships in one state — “townships here handle their own sign permits” — does not transfer across a state border. A township habit that’s safe in one state can be exactly backwards in Illinois or South Dakota, where the correct habit is closer to the opposite: assume the county governs until the township proves otherwise. The wider comparison of which government type actually writes the code, state by state, is in township, county, or city: who writes the code.
How to check which government governs your project
A report identifies whether the applicable government cascades to the county for sign authority — including in Illinois and South Dakota townships, where it happens far more often than the map alone would suggest — so you contact the right office before you file. Creating an account is free.