Permits through August 2026Yearly permits since 1995Mercer County index 1975–2025
Mercer County (100 = first year)United States, rebased to the same startNBER recession
House prices are indexed by county, not by city: this is Mercer County's FHFA index, with the national index rebased to the same start.
Census Bureau notes: building permit figures cover new privately owned housing units authorised by permit-issuing places; permits do not mean the units were started or completed, and places that report less often than monthly are imputed in monthly totals. 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.
Princeton, New Jersey (Mercer County), authorised 123 housing units through building permits in the 12 months to August 2026, −18.5% on the previous 12 months.
34 of those units were single-family houses (28%), 34 were in two- to four-unit buildings and 55 in buildings of five or more units. That is 3.9 units per 1,000 residents, well above the county's 2.3 and above the state's 3.3.
Since 1995 the place has authorised 1,300 units, with the busiest year 2013 (514 units). Mercer County's FHFA house price index rose +87.3% over the ten years to 2025.
123units permitted, 12 months to August 2026−18.5% on the previous 12 months
34single-family units28% of the total
55units in 5+ unit buildings45% of the total
3.9units per 1,000 residentsMercer County 2.3 · New Jersey 3.3
Permits by month and structure type
Housing units authorised in Princeton by month, latest 24 monthssingle-family2+ unit buildings
Units, 12 months to August 2026
Princeton
Mercer County
New Jersey
United States
All housing units
123
929
31,546
1,418,086
Single-family (1 unit)
34 (28%)
497 (53%)
13,153 (42%)
888,241 (63%)
2 units
6
26
1,178
34,814
3–4 units
28
39
929
17,298
5 or more units
55 (45%)
367 (40%)
16,286 (52%)
477,733 (34%)
Units per 1,000 residents
3.9
2.3
3.3
4.1
Change on previous 12 months
−18.5%
−40.6%
−6.2%
−0.1%
Permits by year since 1995
Housing units authorised in Princeton by year, 1995–2025single-family2+ unit buildings
1,300 units since 1995; the busiest year was 2013. Annual figures include units imputed for months a place did not report.
Home prices in Mercer County
FHFA's index for Mercer County rose +87.3% over the ten years to 2025 (+6.5% a year) and +5.7% in the latest year, against +87.7% and +6.2% for New Jersey. Full county page: decade table, peak-to-low declines, every ZIP code and every permit-issuing place in the county.
Questions and answers
How many homes are being built in Princeton, NJ?
123 housing units were authorised by building permits in the 12 months to August 2026, against 151 in the previous 12 months.
What kind of housing is being permitted in Princeton?
34 single-family units, 6 in two-unit buildings, 28 in three- and four-unit buildings and 55 in buildings of five or more units.
How does Princeton compare with its county and state?
3.9 units per 1,000 residents in Princeton, 2.3 in Mercer County and 3.3 in New Jersey.
How have home prices moved in Mercer County?
FHFA's index for Mercer County rose +87.3% over the ten years to 2025 and +5.7% in the latest year; the county page has the full series.
What does a permit count?
A housing unit authorised by a building permit for new privately owned residential construction, as reported to the Census Bureau Building Permits Survey by the permit-issuing office. Permits are not completions; some permitted units are never built, and places that report only annually are imputed in monthly figures.
Provenance
Permits: US Census Bureau, Building Permits Survey, place-level monthly and annual files through August 2026 (permit office 424000); county and state comparisons from the county and state files. Population: Census Bureau vintage 2025 estimates for incorporated places, matched on FIPS place code where the permit office is one. House price index: Federal Housing Finance Agency. Public domain. Corrections · Building Permits Survey.