The Home Building Geography Index (HBGI) is a quarterly measurement of building conditions across the country and uses county-level information about single- and multifamily permits to gauge housing construction growth in various submarkets.
The HBGI classifies each county in the U.S. into one of seven regional categories based on population density and regional location. For each category, NAHB tracked single-family and multifamily growth rates (not seasonally adjusted) and market shares.
Key Findings in the Q4 2021 HBGI:
- Year-over-year single-family growth in all small and large urban, suburban and rural submarkets peaked in the second quarter of 2021.
- Although that expansion has since cooled somewhat, growth rates in all markets remained in double-digits in the final quarter of 2021.
- Multifamily housing growth has been surging since the second quarter, particularly in higher density markets, as the economy more fully reopened in the wake of the Covid crisis.
Download the data file of the full HBGI findings here.
Regional Building Growth Conditions
Starting with the first quarter of 2019, when the Home Building Geography Index was first unveiled, NAHB classified all counties in the U.S. as 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. These categories include:
The Home Building Geography Index is the successor to the Leading Market Index (LMI), whose tracking is no longer maintained. The LMI used single-family housing permits, employment, and home prices to measure proximity to a normal economic and housing market. It was calculated for 337 local markets, metropolitan statistical areas (MSAs), as well as the entire country. View an archive of LMI data with its original methodology.
Update to County Populations
Beginning with the second quarter of 2020, NAHB updated the HBGI to use county population estimates from the 2018 5-year American Community Survey (ACS), as opposed to those from the 2016 5-year ACS. This necessitated a reclassification of county-level regional assignments, based on population density-based delineations. The number of counties that changed their urban classifications in large metro areas was minimal. Most of the regional reclassifications occurred to areas of lower population density. Of the 3,142 counties in the original HBGI, less than 140 counties changed regional classification. There were an additional twenty-three counties in Virginia and two counties in Hawaii that had not been classified previously and were combined with other counties per delineations provided by the Bureau of Economic Analysis. With the new Virginia and Hawaii county delineations, the total number of counties in the HBGI is 3,113.
These new population figures will be applied in forthcoming analyses until later years’ ACS population data become available and implemented, for which there will be announcement.