FHFA annual index 1977–2025Developmental county indexPermits through August 2026
St. Clair County (100 = first year)United States, rebased to the same startNBER recession
FHFA notes: The FHFA HPI is a broad measure of the movement of single-family house prices. The FHFA HPI is a weighted, repeat-sales index, meaning that it measures average price changes in repeat sales or refinancings on the same properties. FHFA describes its county indexes as developmental and subject to revision. The index does not give a dollar value for any home.
FHFA's index for St. Clair County, Illinois, starts in 1977 and stood at 414 in 2025, +314.1% above its base of 100.
Over the ten years to 2025 the index rose +69.3% (+5.4% a year), above Illinois at +64.6% and well below the national +85.0%. The St. Louis, MO-IL area rose +74.5%. The latest one-year change is +5.3%.
The strongest decade was the 1990s (+26.3%); the weakest the 2010s (+5.3%).
After a 2007 peak the index fell −14.5% to 2014 and regained the peak in 2021.
Builders were authorised for 421 housing units in the county in the 12 months to August 2026 (−30.4% on the previous 12 months), 1.7 units per 1,000 residents; 66% were single-family houses. Since 1995 the county has authorised 28,417 units, most in 2004.
+5.3%1 year, 2024–2025Illinois +5.7%
+51.5%5 yearsUS +47.0%
+69.3%10 years+5.4% a year annualised
+97.5%since 2000US +158.3%
421units permitted, 12 months1.7 per 1,000 residents
All columns are FHFA annual all-transactions indexes over the same years.
Decade by decade
Decade
Change
United States
1980s (1980–1990)
+19.4%
+68.2%
1990s (1990–2000)
+26.3%
+33.9%
2000s (2000–2010)
+23.8%
+29.7%
2010s (2010–2020)
+5.3%
+35.5%
2020s so far (2020–2025)
+51.5%
+47.0%
FHFA reports each index with a value of 100 in its base period, the first year the area has enough transactions (1977 here). A decade's change is the index at the end of the decade divided by the index at the start, so it does not depend on the base year; the United States column covers the same years. Decades before 1977 are not shown.
Peak-to-low declines
Peak
Low
Decline
Peak regained
2007
2014
−14.5%
2021
1980
1981
−8.2%
1982
1982
1983
−6.2%
1985
Building permits
Housing units authorised by building permits in St. Clair County, by month over the latest five years and by year since 1995.
Housing units authorised in St. Clair County by month, latest 12 monthssingle-family2+ unit buildings
Housing units authorised in St. Clair County by month, latest 60 monthssingle-family2+ unit buildings
Housing units authorised in St. Clair County by year, 1995–2025single-family2+ unit buildings
Permits, 12 months to August 2026
St. Clair County
Illinois
United States
Housing units authorised
421
19,157
1,418,086
Units per 1,000 residents
1.7
1.5
4.1
Single-family share
66%
56%
63%
Change on previous 12 months
−30.4%
−5.7%
−0.1%
Units authorised since 1995
28,417
1,034,461
43,082,761
Population is the Census Bureau's vintage 2025 estimate. Permits authorise construction; they are not completions.
ZIP codes in St. Clair County
Ranked by ten-year change in the FHFA ZIP index. Where a ZIP's index ends before 2025, its spans end in that year.
How much have home values in St. Clair County risen over 10 years?
The FHFA index for St. Clair County rose +69.3% from 2015 to 2025, about +5.4% a year. Over 20 years: +55.6%; since 2000: +97.5%.
How does St. Clair County compare with Illinois and the United States?
Over the ten years to 2025: St. Clair County +69.3%, Illinois +64.6%, United States +85.0%, St. Louis, MO-IL +74.5%.
What happened to St. Clair County prices in 2008?
The index peaked in 2007 and fell −14.5% to 2014; it passed the peak again in 2021. The state index fell −23.2% over 2007–2012.
How many homes are being built in St. Clair County?
421 housing units were authorised by building permits in the 12 months to August 2026 (278 single-family, 49 in buildings of five or more units), or 1.7 per 1,000 residents against 1.5 for Illinois.
Where does this data come from?
The index is FHFA's annual county house price index (all-transactions, developmental), last updated March 31, 2026, with values through 2025. Permits are from the Census Bureau Building Permits Survey through August 2026; population is the Census Bureau's vintage 2025 estimate.
Provenance
Index: Federal Housing Finance Agency, annual house price index for counties (all-transactions, developmental), last updated March 31, 2026, values 1977–2025; metro, state and national comparisons from FHFA's annual indexes in the same release. Permits: Census Bureau Building Permits Survey, county and place files, through August 2026. Population: Census Bureau vintage 2025 estimates. ZIP assignment: 2020 ZCTA-to-county relationship file. Public domain throughout. Corrections · FHFA HPI datasets · Building Permits Survey.