Arbitrary-year county crosswalks.get_crosswalk() now supports county -> county crosswalks between any pair of years from 2000 through 2025 (e.g., 2014 -> 2019 or 2014 -> 2023), accounting for counties redefined outside decennial censuses: Broomfield County, CO created (2002 vintage); Clifton Forge, VA merge (2002); the 2007-2008 southeast Alaska reorganizations (2008-2009); the York/Newport News, VA territory exchange (2008); the Bedford, VA merge and Petersburg Borough, AK reorganization (2014); the Shannon -> Oglala Lakota, SD and Wade Hampton -> Kusilvak, AK FIPS changes (2015); the Valdez-Cordova, AK split (2020 vintage); and the Connecticut planning regions (2022). Crosswalks compose all events in the requested interval on top of an identity mapping over the full county universe, with population-based allocation factors for splits and part transfers. County crosswalks are forward-only. The event registry, mappings, and county universes are curated from the Census Bureau’s “Substantial Changes to Counties and County Equivalent Entities” documentation by data-raw/build_county_events_sysdata.R and shipped as internal package data, so county requests work offline.
Sub-county geographies affected by county changes. Tract, block group, and block crosswalks are available for same-decade year pairs from 2010 onward (e.g., tract 2014 -> 2019), applying county-prefix relabels for FIPS renames/merges and the CT Data Collaborative crosswalk for Connecticut’s 2022 change. Year pairs spanning a decennial census (e.g., tract 2014 -> 2023) are planned automatically as chains through NHGIS crosswalks, including exact backward relabels to reach an NHGIS-served vintage (e.g., tract 2017 -> 2023 plans 2017 -> 2014 -> 2020/22 -> 2023).
The chain planner’s temporal-path search now spans multiple sources: hops are tagged with the crosswalk source that serves them, and NHGIS is preferred when both NHGIS and the county-events engine can serve a hop. get_available_crosswalks() lists the new county-events combinations.
Multi-step plans whose final GeoCorr step targets a year with county codes differing from the GeoCorr vintage now emit a warning.
crosswalk_data() now always computes and attaches the join_quality attribute; show_join_quality = FALSE and silent = TRUE suppress only the printed diagnostics. Previously, disabling the messages also silently omitted the attribute.
get_available_crosswalks() gains a crosswalk_source column identifying which source serves each combination, and now lists each combination exactly once: the 2020 <-> 2022 pairs, which both CTData and the county-events engine can serve, are listed under ctdata_2020_2022, mirroring how get_crosswalk() routes direct requests.
Documentation
Three new vignettes: vignette("crosswalk") (getting started; the core workflow, multi-step chains, metadata, join quality, caching), vignette("how-interpolation-works") (what the interpolation math assumes, choosing a weight, accuracy against published values, diagnosing joins), and vignette("county-crosswalks") (county change events and arbitrary-year county crosswalks).
The “Standardizing Longitudinal Data” vignette is now precomputed from vignettes/standardizing-longitudinal-data.Rmd.orig (see vignettes/precompile.R), so building the package requires neither network access nor an IPUMS API key. It also now displays the join-quality diagnostics it narrates and closes with a worked example of a split tract’s six-year series.
The structures of the join_quality and crosswalk_metadata attributes are now fully documented (in ?crosswalk_data and ?get_crosswalk respectively), along with caching read-back behavior, the empty-crosswalk return for nested geographies, and multi-step attribute semantics.
Added a package-level help topic (?crosswalk) and a curated pkgdown reference index; the README was slimmed to a quick start that links to the vignettes.
Breaking changes
get_crosswalk() now filters NHGIS crosswalks to a single interpolation weight matching the weight argument ("population", "housing", or "land"). Previously, NHGIS crosswalks were returned in long format with one row per source-target pair per weighting factor (typically eight rows per pair), and applying them with crosswalk_data() silently multiply-counted values by roughly the number of weighting factors. NHGIS weighting_factor values no longer carry a weight_ prefix (e.g., "population" rather than "weight_population").
crosswalk_data() now errors when a crosswalk contains multiple rows per source-target GEOID pair (which would multiply-count values), and when the input data contains duplicated GEOIDs (panel data must be split by period and crosswalked separately).
crosswalk_data() no longer emits a geoid = NA row aggregating data rows that failed to match the crosswalk; unmatched rows are dropped and reported via the join_quality attribute.
crosswalk_data() now renames only target_geoid -> geoid and target_geography_name -> geography_name in its output; user columns containing the string “target_” are no longer mangled.
Bug fixes
NHGIS 1990 tract GEOIDs are now right-padded with the implied "00" tract suffix, so all 1990 tract GEOIDs have the standard 11 characters (previously ~66% of rows had 9-character GEOIDs).
Cached NHGIS and GeoCorr crosswalks are now read back with explicit column types; previously, type-guessing could silently strip leading zeros from GEOIDs (e.g., ZCTA "00601" became 601) on cache reads.
GeoCorr 2018 block-level queries are now chunked into groups of at most 13 states; previously, chunks of 17 states exceeded the GeoCorr API limit.
Block-level GeoCorr crosswalks assembled from multiple chunked requests no longer retain the human-readable label row of each chunk after the first.
Numeric crosswalk columns (allocation_factor_target_to_source, population_2020, housing_2020, land_area_sqmi, etc.) are no longer coerced to character by get_crosswalk().
When only source_year is provided, the GeoCorr version is now selected from the source year; previously get_crosswalk(..., source_year = 2015) silently used GeoCorr 2022 (2020 Census geography).
The nested-geography check in get_crosswalk() now recognizes alternate spellings (e.g., "blockgroup", "bg").
NHGIS download failures (e.g., an invalid API key) now raise a clear error with the HTTP status instead of a warning about an empty zip file.
The api_key argument to the internal NHGIS fetcher is no longer ignored.
County 2020 -> 2022 crosswalk metadata no longer claims all allocation factors equal 1 (Connecticut county records are population-weighted).
get_ctdata_crosswalk() now fails informatively when tidycensus is not installed (county crosswalks only).
crosswalk 0.0.0.9001
Support for chains of three or more crosswalks.
Silent mode via silent argument and the crosswalk.silent option.