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Data · Crosswalks

Practice areas, court districts and counties, in one table

One reference table for joining legal market data. Every county and county equivalent, in the states and the territories, with its federal court district, division, metro area and population; every federal district with its circuit and court ids; and a practice-area list that links each area to its federal case codes, to the FOLIO legal ontology and to the Probative datasets that measure it. Districts are read from the U.S. Code and checked against the U.S. Courts county tables.

Checked October 29, 2026 · CC BY 4.0 · Not legal advice

What is in this dataset?

The shared keys that join every Probative dataset. One record per practice area (our taxonomy of consumer and business practice areas, each linked to the FOLIO Area of Law class it matches, the federal nature-of-suit codes of its cases, the site's practice pages and the datasets that measure its demand, supply, rules and money), per federal nature-of-suit code, per state and territory (FIPS and postal codes, Census region and division, federal circuit and districts), per federal judicial district (our district key, the Federal Judicial Center code and the court's CM/ECF id), per county and county equivalent in the 50 states, DC and the territories (Puerto Rico's municipios and the county equivalents of Guam, the U.S. Virgin Islands, the Northern Mariana Islands, American Samoa and Midway: FIPS code, the federal district and statutory division it belongs to, its metro or micro area and its Census population), per former county code older sources still use (with the current counties that took its area), and per documented source code that names a place under another key (EEOC's WQ for Wake Island) or is not a place at all (military mail, the freely associated states, the VA's unplaced addresses, U.S. Courts' outside-the-U.S. code). Every county's district is read from the statute and checked against the counties U.S. Courts lists under each district in its bankruptcy Table F-5A.

Use it to join any two Probative datasets, or our data with your own: a county FIPS code gives the federal district whose filings and bankruptcy figures apply to it, a practice area gives the federal case codes and the datasets that measure it, and a district key gives the counties and population it covers. Agents can resolve a place or a practice to the right keys before calling any other Probative dataset.

Records
3,648
Look up by
58
jurisdiction
Primary source
3,475
Secondary source
50
Default
123

The letters are explained in what P, S, D and U mean.

Where does the data come from?

Counties and populations come from the Census Bureau's vintage 2025 estimates (Puerto Rico's municipios from its vintage 2025 municipio estimates, the other territories' county equivalents from the Census 2020 county code list with their 2020 Census counts); each county's federal district and division is read from 28 U.S.C. chapter 5 (Virginia's independent cities by section 127(c)) and checked against the counties U.S. Courts lists under each district in Table F-5A; circuits from 28 U.S.C. section 41; the territories' districts from 28 U.S.C. section 119 and 48 U.S.C. sections 644a, 1424, 1611 and 1821; former county codes and their successors from the Census county code lists, its Substantial Changes to Counties pages and its Connecticut crosswalk; metro areas from the July 2023 OMB delineation; nature-of-suit codes from the U.S. Courts code descriptions (Rev. 06/26); practice areas and their links are Probative's own classification, mapped to FOLIO class ids.

Period covered
2026
Places
The whole US, states, counties, metro areas and federal court districts
How often we refresh it
Once a year
The source's next release
March 2027
Records read
October 29, 2026

Official sources

The sources the records cite most

What does a record look like?

The full records add the dates, the quoted source text and every field in the CSV and JSON files below.

What each of the 35 main columns means
jurisdiction
Two-letter state or territory code the record belongs to, or US for the national tables (practice areas, case codes, datasets, special keys)
table
STATE, DISTRICT, COUNTY, FORMER (a county code no longer current that older sources still use), ALIAS (another code a source uses for a place that has a key here), SPECIAL (a code a source uses that is not a U.S. place), PRACTICE, NOS (federal nature-of-suit code) or DATASET
code
The record's key in its table: a postal code, a district key (CAC, NYS), a 5-digit county FIPS code, a source's alias or special code (WQ, OTHER), a practice-area id, a 3-digit nature-of-suit code or a dataset id
name
Name in English
nameEs
Name in Spanish (county names are proper names and stay as the Census Bureau writes them)
status
P read from the primary source; S secondary: a nature-of-suit code no longer on the current U.S. Courts list (kept for older cases), a Virginia independent city placed by 28 U.S.C. 127(c) using the U.S. Courts county lists, or a former county code in a multi-district state placed by the district of its successors; D Probative's own classification (practice areas and dataset links)
value
STATE and COUNTY: residents on July 1, 2025 (Census estimate), or on April 1, 2020 (2020 Census) for Guam, the Virgin Islands, the Northern Mariana Islands and American Samoa, which have no annual estimates (the unit says which); empty for Midway, which the Census Bureau does not count; DISTRICT: residents of its counties; empty for the other tables
fips
STATE: the 2-digit state FIPS code
state
Postal code of the state the district or county is in
district
COUNTY and FORMER: the federal judicial district it belongs to, as a district key (the form the civil-filings, idb-civil and mdl datasets use); empty for American Samoa, which has no federal district court
districtDivision
COUNTY: the statutory division of the district, where the statute divides it
circuit
Federal court of appeals circuit (28 U.S.C. section 41)
cbsa
COUNTY: the 2023 core-based statistical area code (metro or micro area); empty outside any
cbsaTitle
COUNTY: the metro or micro area's name
cbsaType
COUNTY: metro or micro
region
STATE: Census region
division
STATE: Census division
districts
STATE: the federal judicial districts in it (the U.S. Minor Outlying Islands: the District of Hawaii, 48 U.S.C. 644a)
territory
STATE: true for Puerto Rico, Guam, the U.S. Virgin Islands, the Northern Mariana Islands, American Samoa and the U.S. Minor Outlying Islands
successors
FORMER: the current county FIPS codes that took the former county's area (from the Census change pages or, for Connecticut, the Census planning-region crosswalk)
target
ALIAS: the postal code of the place the alias stands for
kind
SPECIAL: what the code is (military mail, freely associated state, court code, unplaced)
idbCode
DISTRICT: the Federal Judicial Center Integrated Database circuit and district code
ecfId
DISTRICT: the district court's CM/ECF id (ecf.<id>.uscourts.gov), the id CourtListener also uses; empty if the host does not resolve
bankruptcyEcfId
DISTRICT: the bankruptcy court's CM/ECF id; empty where the territorial district court hears bankruptcy cases
parent
PRACTICE: the parent practice area; empty for a top-level area
level
PRACTICE: 1 top-level, 2 sub-area
sitePractice
PRACTICE: the practice page family on probativegrowth.com it feeds
folioIri
PRACTICE: the FOLIO Area of Law class it maps to (folio.openlegalstandard.org; FOLIO data is CC BY 4.0)
folioMatch
PRACTICE: exact, close, broad (FOLIO's class is wider) or narrow
nos
PRACTICE: federal civil nature-of-suit codes whose cases belong to it
naics
PRACTICE: the NAICS industry code of the firms that practise it
practices
NOS and DATASET: the practice areas linked to the code or measured by the dataset
dimensions
DATASET: what it measures: demand, supply, rules or money
doi
DATASET: the dataset's current version DOI

How do I use it in my own tools?

crosswalks_lookup
For one two-letter state or territory code (PR, GU, VI, MP, AS and UM included): the state record, its federal districts, every county or county equivalent with its FIPS code, district, division, metro area and population, its former county codes with their successors and any alias codes. Use US for the practice-area taxonomy, the federal nature-of-suit codes, the dataset links and the special (non-place) codes.
crosswalks_compare
The same records for up to 10 two-letter state codes.
crosswalks_search
Records whose text matches the words given, such as a county name ("Harris County", "San Juan Municipio"), a FIPS code (current or former, "02201"), a district key ("CAC"), a source code ("WQ"), a practice area ("truck accidents") or a case type ("Telephone Consumer Protection Act").

How to cite this dataset

You can reuse, adapt and republish this data, including commercially, under the Creative Commons Attribution 4.0 license (CC BY 4.0). The only condition is that you credit Probative and link to the source.

Version
1.1.0, released October 28, 2026
Every version
10.5281/zenodo.23741881 (always points to the newest)
License
CC BY 4.0

Download the data

Free, no email or login. The files are hosted on this site and Zenodo, a public research archive.

Suggested citation

Probative. (2026). Legal market crosswalks: practice areas, federal case codes, states, federal districts and counties (Version 1.1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.23744618

Credit line for a chart, table or article

Source: Probative, Legal market crosswalks: practice areas, federal case codes, states, federal districts and counties, version 1.1.0, https://doi.org/10.5281/zenodo.23744618, licensed CC BY 4.0.

Add to a reference manager (Zotero, Mendeley, EndNote)

Not legal advice. This is a reference table of public codes and boundaries, kept for research and marketing planning. Which court hears a case depends on more than a county line; check the statute and the court's own rules.

What changed recently?

  • 2026-10-28 · Practice areas, nature-of-suit codes, states, federal districts, counties and the datasets that measure each practice, with the keys every Probative dataset uses. (source)
  • 2026-10-28 · Puerto Rico's municipios and the county equivalents of Guam, the U.S. Virgin Islands, the Northern Mariana Islands, American Samoa and Midway join the county table, each with its federal district (where one exists) and its Census population; the U.S. Minor Outlying Islands become a jurisdiction. Former county codes retired since the 1970s (such as Alaska's Prince of Wales-Outer Ketchikan, 02201) join the former-code table, and every former code now names the current counties that took its area. Codes sources use for a place under another key (EEOC's WQ for Wake Island, U.S. Courts' NMI) and for things that are not places (military mail, the freely associated states, the VA's unplaced addresses) are documented as ALIAS and SPECIAL rows. (source)

The full log is in changes.json.

What are the limits?

  • A county's federal district is where the statute puts the county. Where a case is filed also depends on where the parties live, where the events happened and the court's own venue rules.
  • A few districts share or split land the county grid cannot show: military bases in North Carolina that belong to the Eastern District although their counties belong to the Middle District, and waters that New York's Southern and Eastern Districts share. The county is keyed to the district the statute lists it under.
  • Virginia's independent cities are not named in the statute; it places each with the county it lies in or was formed from. We place them by the district U.S. Courts lists them under and mark those records as placed by us.
  • The practice-area list and its links to datasets are our own classification. The FOLIO match says how close our area is to FOLIO's class (exact, close, broader or narrower); FOLIO has no class for some consumer areas such as DUI defense or Social Security disability.
  • The territories are in: Puerto Rico's municipios, Guam, the islands of the U.S. Virgin Islands, the municipalities of the Northern Mariana Islands, the districts and islands of American Samoa, and Midway. Puerto Rico's populations are the latest Census estimates; the other territories have only the last decennial Census count, and Midway has none. American Samoa has no federal district court, so its rows have no district.
  • Former county codes (such as Alaska's retired Prince of Wales-Outer Ketchikan Census Area) list the current counties that took their area. Where a former county was split, a record from an older source cannot be placed in one of them; it still belongs to one federal district.
  • Some sources use codes that are not places: military mail, the freely associated states (Palau, the Marshall Islands, Micronesia), addresses outside the U.S. and unplaced addresses. They are listed so every key resolves, and they count only in national totals.
  • Records older than 400 days since their last check are marked stale in the files until we re-check them. Every confirmed error we fix is listed in the data corrections log.

Found a wrong value? Report an error with the record id and the source that shows the right value.

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