Small-Area Summaries of the Historical Built Environment

The NHGIS HISDAC-US Small-Area Summaries of the Historical Built Environment provide a range of information about past characteristics of human settlement, including land use since 1940 and built-up extents since 1900, summarized for each 2010 census tract throughout the contiguous U.S.

Overview

The current version of the Small-Area Summaries of the Historical Built Environment is derived from the Historical Settlement Data Compilation for the US, Version II (HISDAC-US v2; Ahn et al., 2024). The HISDAC-US source data are raster layers summarizing various building-level and property-level characteristics, by 250-meter grid cell, based on data from Zillow's Transaction and Assessment Dataset (ZTRAX), ParcelAtlas, and Open City Model (OCM). These sources provide data for present-day features, and HISDAC-US derives historical characteristics from them by using built-year information to identify which buildings were likely to have existed at different times in the past.

The tract-level summaries and the accompanying documentation were prepared by the HISDAC-US research team at the University of Colorado Boulder, working in coordination with IPUMS NHGIS staff, for distribution through NHGIS.

There are three summary files in this dataset, each summarizing different characteristics across a different time period:

NHGIS_HISDAC_Tract10_LUxYear
Land use by year, 1940–2020, decadal intervals
- This file provides counts of records for each of eight land use classes (Agricultural, Commercial, Recreational, Residential-Income, Residential-Owned, Governmental, and Vacant Land)
NHGIS_HISDAC_Tract10_BUxYear
Built-up property characteristics by year, 1900–2020, decadal intervals
- This file contains four summary statistics, each derived from a different HISDAC-US layer:
  - BUA (built-up area): Proportion of tract area lying in a 250m raster cell with at least one built-up property
  - BUI (built-up intensity): Total indoor building area in square feet
  - BUPL (built-up property locations): Number of unique built-up property locations (i.e., buildings)
  - BUPR (built-up property records): Number of individual built-up property records (i.e., buildings or units within a building)
NHGIS_HISDAC_Tract10_BuiltYearSummary
Summaries of built-year information and completeness by tract
- This file includes two summaries of buildings' built years (minimum and average) along with two indicators of the quality of the data by census tract:
  - The proportion of built-up property locations with no built year information, i.e., the proportion of cases that are omitted from historical HISDAC-US summary statistics for this tract (in this and other files)
  - The ratio of built-up property locations (BUPL) of 2020 to the respective epoch of the Microsoft Building Footprints, i.e., an indicator of HISDAC-US quality and completeness based on its agreement with a satellite-derived source of building locations
- The file also includes the base counts used to compute the above quotients

Technical Details

Data Sources

There are two main input datasets:

HISDAC-US V2 raster layers
IPUMS NHGIS 2010 census tract GIS boundary file, 2010 TIGER/Line+ basis

Software Used

To compute zonal statistics summarizing characteristics from the HISDAC-US raster layers for each 2010 census tract, we used the exactextractr package in R.

Split Grid Cells & Non-Integer Counts

Where input grid cells straddle census tract boundaries, the exactextractr sum operation distributes fractions of cell values among intersecting tracts in proportion to their areas of overlap. This produces non-integer results for count statistics such as BUPL_ALL and the land use summaries. The summary files provide these results as floating-point numbers, without rounding, in order to maintain the correct totals across all tracts.

Geographic Coverage

The summaries are limited to the contiguous U.S., excluding Alaska, Hawaii, and Puerto Rico, because the HISDAC-US source data do not fully cover these areas.

There are 72,539 2010 census tracts in the contiguous U.S., but the summaries cover only the 72,271 census tracts that are in the NHGIS boundary data for these areas. The difference is due to the NHGIS boundaries omitting areas that lie entirely in coastal or Great Lakes waters.

Special Values

The data summaries use a value of -99 to indicate NA (not applicable) or no data.

Data Quality Issues

The HISDAC-US source data are subject to a variety of quality issues. The HISDAC-US team has identified and documented the main issues in various publications (Leyk and Uhl 2018, Uhl et al. 2021, McShane et al. 2022, Ahn et al. 2024). In particular, users should be aware that there are areas of uncorrected missingness, systematic overcounts, and extreme outliers:

Missingness: There are a number of tracts that contain Microsoft Building Footprints but no HISDAC-US records. There are also numerous records in HISDAC-US sources that lack a built year and therefore cannot be included in HISDAC-US historical characteristics. We recommend that users inspect the completeness indicators provided in the NHGIS_HISDAC_Tract10_BuiltYearSummary file. With these, it is possible to identify tracts with unacceptably low rates of HISDAC-US coverage and omit these tracts from analyses.
Systematic overcounts: HISDAC-US's BUPL record counts tend to be higher than the Microsoft Building Footprint counts. This overcount might be caused by effects of double-counting or the inclusion of buildings or building parts that are not included in the Microsoft Building Footprints.
Extreme outliers: In some instances, the HISDAC-US summary statistics are exceptionally high or low relative to the Microsoft Building Footprint counts, relative to census counts, or relative to each other. For example, the indoor built-up area (BUI) is in some cases a few times higher or lower than may be expected given the number of built-up locations (BUPL). In many of these cases, the source of the problem is that a single "default location" (possibly a county or city centroid) has been assigned to a large set of buildings that individually lack precise geolocational information.

Download

NHGIS provides all three summary files along with a README text file in this ZIP archive:

NHGIS_HISDAC_Tract10.zip (45.4 MB)

Citation and Use

Use of the NHGIS HISDAC-US Small-Area Summaries of the Historical Built Environment is subject to the same conditions as for all NHGIS data:

You will not redistribute the data without permission.
You will cite the source appropriately.

Publications or research reports should include the following product-specific citation:

Berg, A. K., Leyk, S., Noi, E., Ahn, Y., Uhl, J. H., Ren, Y., Davydzenka, T., Schroeder, J., Van Riper, D. Small-Area Summaries of the Historical Built Environment from HISDAC-US: Version 1.0 [dataset]. IPUMS National Historical Geographic Information System. Minneapolis, MN: IPUMS. 2026. https://doi.org/10.18128/D051.V1

Credits

The production of the Small-Area Summaries of the Historical Built Environment was supported by funding from the National Science Foundation (BCS 2121976).

References

Ahn, Y., Leyk, S., Uhl, J.H., & McShane, C. M. (2024). An Integrated Multi-Source Dataset for Measuring Settlement Evolution in the United States from 1810 to 2020. Scientific Data 11:275. https://doi.org/10.1038/s41597-024-03081-x
Leyk, S. & Uhl, J.H. (2018). HISDAC-US: Historical Settlement Data Compilation for the Conterminous United States Over 200 Years. Scientific Data 5:180175. https://doi.org/10.1038/sdata.2018.175
McShane, C., Uhl, J. H., & Leyk, S. (2022). Gridded land use data for the conterminous United States 1940–2015. Scientific Data, 9:493. https://doi.org/10.1038/s41597-022-01591-0
Uhl, J. H., Leyk, S., McShane, C. M., Braswell, A. E., Connor, D. S., & Balk, D. (2021). Fine-grained, spatiotemporal datasets measuring 200 years of land development in the United States. Earth System Science Data, 13(1), 119-153. https://doi.org/10.5194/essd-13-119-2021