Home Building Geography Index (HBGI)

The Home Building Geography Index (HBGI) is a quarterly measurement of building conditions across the country and uses county-level information about single-family and multifamily permits to gauge housing construction growth in various submarkets. The HBGI for the fourth quarter of 2025 focuses on the population density-based delineation of home building that has been the mainstay of the HBGI.

Key Findings for Q4 2025:

• Single-family construction declined in all regions except micro counties, which saw a 1.6% increase and marked their seventh consecutive quarter of growth.
• Multifamily construction increased across every geographic region, with micro counties leading growth at 14% on a year over year four quarter moving average.
• Market share shifted toward smaller and lower-density areas in both single family and multifamily sectors, highlighting affordability and space needs as key drivers of construction activity.

Download the data file of the full HBGI findings

Regional Building Growth Conditions

NAHB classified all counties in the U.S. into one of seven regional categories based on population density and regional location. For each area, NAHB tracked single-family and multifamily growth rates (not seasonally adjusted) and market shares. An interactive map of the latest data is shown below, followed by definitions of each category.

Definitions of Regional Categories

• Large Metro Core Counties
  • Densely populated central counties within major metropolitan areas (over 1 million population). These are the urban cores with the highest population density.
• Large Metro Suburban Counties
  • Suburban counties surrounding the core of major metros (over 1 million). They are less dense than core counties but still part of large urban regions.
• Large Metro Outlying Counties
  • Counties on the outer edge of major metro areas, typically lower density and farther from the urban core but still tied economically to large metros.
• Small Metro Core Counties
  • The central counties of smaller metropolitan areas (under 1 million population). They are the most populated/dense part of smaller metro regions.
• Small Metro Outlying Counties
  • Lower-density counties located on the periphery of small metropolitan areas.
• Micro Counties
  • Low‑density, low‑population counties that form micropolitan areas, typically centered around small towns with 10,000–50,000 residents. These counties saw notable construction growth.
• Non metro/micro counties
  • The most rural areas with no metro or micropolitan designation, very low density and population.

Update to County Populations

Beginning with the second quarter of 2022, NAHB updated the HBGI to use the most recent county population estimates from the 2020 5-year American Community Survey (ACS). This necessitated a reclassification of county-level regional assignments, based on population density-based delineations. The number of counties in the HBGI is 3,133, with the newest updates for counties in Virginia and Hawaii.