Building permits as an early signal for ICCSD enrollment
Corridor housing permits, 2010 to 2025, with the address-level ICCSD vs Clear Creek-Amana
split from the geocoded pull
New single-family homes today become kindergarteners in about five years. The
enrollment forecast turns on one number, the share of county births that enrolls in ICCSD
kindergarten. That share moves with where families build and buy. In the ICCSD corridor,
single-family permits lead the kindergarten share by about five years, with a correlation of
+0.76 at a four-year lag (+0.59 at five). The new address-level data
sharpens the picture by separating ICCSD building from Clear Creek-Amana.
Lead correlation
+0.76
ICCSD-core single-family permits to K share, 4-yr lag
Unincorporated county that is ICCSD
24%
geocoded, 2021-2025 (61 of 253 units)
ICCSD-core single-family permits
stable
253 to 365 a year, 2020-2025
Where the family housing is getting built
Single-family detached homes are the housing that brings school-age children. Multifamily, mostly
student and young-professional rentals near the university, brings very few. So the single-family
permit trend is the part that matters for enrollment.
Single-family permits by city, 2010 to 2025
Iowa City proper is largely built out, and its single-family permits have drifted down. North
Liberty is the ICCSD growth engine and keeps building at a steady pace. Tiffin, which sits in Clear
Creek-Amana, surged from about 36 single-family permits in 2016 to 120 to 163 a year from 2017
through 2021, then cooled back to about 110.
The ICCSD vs CCA split, from geocoding
The earlier version of this analysis had to treat whole cities and the whole unincorporated county
as ICCSD. The address-level pull fixes that. Every unincorporated-county permit from 2021 to 2025 was
geocoded and assigned to a school district by point-in-polygon against the Census district boundary.
The result is a clean read on who is actually capturing rural growth.
Unincorporated Johnson County new homes by school district (geocoded, site-built)
Most rural building is not ICCSD. Of 253 site-built homes permitted in
unincorporated Johnson County over 2021 to 2025, only 61 (24%)
fall in ICCSD. Clear Creek-Amana took 36, and 156 went to other
districts entirely, mostly College Community (Prairie), Solon, and Lone Tree. This corrects the
earlier assumption that unincorporated growth was ICCSD. It is not. ICCSD's family-housing base is
the incorporated core, not the rural fringe.
The corridor, attributed
Jurisdiction (all new units)
2021
2022
2023
2024
2025
5-yr
ICCSD attribution
Split status
Iowa City
294
466
506
133
161
1560
100% ICCSD
confirmed
Coralville
174
397
154
120
260
1105
most ICCSD
city pending
North Liberty
278
126
308
134
520
1366
most ICCSD
city pending
Tiffin
271
285
172
244
206
1178
mostly CCA
city pending
Johnson Co. uninc. (site-built)
42
54
54
45
58
253
61 of 253 ICCSD (24%)
geocoded
Iowa City sits entirely inside ICCSD, so its new units are all ICCSD. The unincorporated county is
now geocoded. Coralville and North Liberty are predominantly ICCSD but have Clear Creek-Amana slices
on their western edges, and their city permit portals blocked a clean address-level pull this round.
Tiffin is primarily Clear Creek-Amana.
The permits lead the kindergarten share
ICCSD-core single-family permits (lagged 5 yr) vs the K-entry share
ICCSD-core here means Iowa City plus Coralville plus North Liberty, the incorporated cities that
are entirely or predominantly ICCSD. The unincorporated county is left out, because the geocoding
shows it is mostly other districts. The two lines still move together, and the relationship holds
(+0.76 at four years), so the corrected series works as an early signal.
What it says about the forecast
The permits point to stabilization, not further decline. The kindergarten classes
of 2026 to 2030 draw on permits from about 2020 to 2025. Over those years ICCSD-core single-family
permits held steady, between 253 and 365 a year, with no further drop. The Tiffin
surge that pulled the share down has passed its peak, and the incorporated core that actually feeds
ICCSD kept building. This supports the Baseline (a flat share near 0.718) and
argues against the Low scenario, which assumes the share keeps falling toward
0.680. It also reframes the geographic drain. It is not only Tiffin. The whole rural fringe of the
county builds mostly for other districts, and ICCSD captures its incorporated core.
The honest limit
Two of the suburbs are still whole-city totals. The geocoding is complete for
Iowa City (all ICCSD) and the unincorporated county. Coralville and North Liberty still come in as
whole-city BPS totals, because their permit portals blocked a clean address-level pull. Both are
predominantly ICCSD with small Clear Creek-Amana slices, so the ICCSD-core series is close but not
exact. A records request to those two cities would finish the split and let the permits feed the
kindergarten module directly.
Multifamily permits are excluded on purpose. They bring few school-age children.
Manufactured-home placements are excluded. They are mostly replacements, not net-new.
The lead correlation rests on eight non-COVID kindergarten years, so it is directional, not a
fitted model.
Source: Building Permits (Tier 1) fact_units_ts.csv (U.S. Census Building Permits
Survey, place-level, single-family = 1-unit bucket) and fact_permit.csv (address-level, geocoded with
the Esri World Geocoder and assigned to school districts by point-in-polygon against Census TIGERweb
Unified School Districts, 2024 vintage). Unincorporated permits from the Johnson County CitizenServe
issued-permits report, 2021 to 2025. Pulled 2026-06-30. Built iccsd-enrollment-permits.html via
scripts/build_permit_indicator.py.