Datasets and Spatial Tools for United States Homelessness Research • COCHomeless

Datasets and spatial tools for United States homelessness research. COCHomeless packages HUD Continuum of Care (CoC) Point-in-Time (PIT) homeless counts, CoC boundaries, a Census-to-CoC crosswalk, and county-level homeless estimates, covering 2007–2025.

Installation

# install.packages("remotes")
remotes::install_github("SSDALab/COCHomeless", build_vignettes = TRUE)
library(COCHomeless)

sf is required (spatial objects). tidycensus, ggplot2, tigris, imputeTS and a few others are only needed to rebuild data or run the vignettes.

Coverage

All series run 2007 through 2025 (annual). The 2025 PIT counts are HUD’s official release; hud2025_prelim keeps the earlier Community Solutions estimate for reference. In 2021 HUD waived the unsheltered count for many CoCs during COVID-19, so 2021 understates homelessness — the vignettes show an ARIMA reconstruction.

Three forms of data

1. CoC level (HUD administrative areas)

Object	What
`hud2007` … `hud2025`	PIT “Overall Homeless” count per CoC, by year
`coc2007` … `coc2025`	CoC boundary polygons (national `sf`), by year
`coc_mergers`	CoC merger crosswalk over time (code lineage)
`pit_us`	national totals split into sheltered / unsheltered
`pit_coc`	per-CoC sheltered / unsheltered / total, 2007–2025
`pit_coc_detail`	per-CoC by shelter type × subpopulation (veterans, chronic, youth, families, gender, race, age)
`hud2025_prelim`	preliminary 2025 estimate (superseded by `hud2025`)

CoC boundaries (coc20XX) also carry that year’s total/sheltered/unsheltered.

2. Census ↔︎ CoC crosswalk (links Census tracts/counties to CoCs)

Object	What
`tract_coc2007` … `tract_coc2025`	tract → CoC hard assignment, by year
`tract_coc_wt2007` … `tract_coc_wt2025`	tract ↔︎ CoC area weights, by year
`county_coc2007` … `county_coc2025`	county ↔︎ CoC weights (both directions), by year

Tract geography uses 2010-census tracts for 2007–2019 and 2020-census tracts for 2020–2025.

3. County-level estimates (CoC counts disaggregated to counties)

Object	What
`homeless`	county estimates `count07`…`count25` + ACS covariates (imputed)
`homeless_na`	same, before imputation (missing counties as `NA`)
`sp_homeless`	`homeless` as `sf`, also carrying `sheltered<yy>`/`unsheltered<yy>`
`county_pit`	county sheltered / unsheltered / total, 2007–2025 (long)
`county_pit_detail`	county by shelter type × subpopulation (gender, race, age, …)
`counties`, `states`	full-US `sf` base layers
`area`	county land area (km²)

Vignettes

After installing with build_vignettes = TRUE:

browseVignettes("COCHomeless")

CoC Point-in-Time homeless counts (coc-pit-counts) — national & state maps, per-CoC trends, sheltered/unsheltered series with ARIMA reconstruction of 2021.
County-level homeless estimates (county-estimates) — county-vs-CoC comparison, per-capita maps, US/CA/WA trends, a 2025 summary grid.
Census-to-CoC crosswalk (census-coc-crosswalk) — using the crosswalk and coc_mergers.

Vignette sources are in vignettes/; build scripts that regenerate every dataset from source are in data-raw/.

Methodology & citation

County estimates disaggregate CoC PIT counts by population density and impute counties with no CoC, following Almquist, Helwig & You (2020). Please cite:

Almquist, Z. W., Helwig, N. E., & You, Y. (2020). Connecting Continuum of Care point-in-time homeless counts to United States Census areal units. Mathematical Population Studies, 27(1), 46–58. https://doi.org/10.1080/08898480.2019.1636574

The Census-to-CoC crosswalk follows Tom Byrne’s HUD-CoC-Geography-Crosswalk; please credit it when using the tract_coc* / county_coc* data. Run citation("COCHomeless") for full details.

ACS pulls need a Census API key in ~/.Renviron (CENSUS_API_KEY); never commit it.