Data Sources & Methodology

Overview

KingSt.com compiles congressional data from public, freely available sources. Every dataset we use is either in the public domain (CC0 licensed) or available through official government APIs at no cost. This page describes each data source, what we use it for, and how we process it.

unitedstates/congress-legislators

Repository: github.com/unitedstates/congress-legislators

License: CC0 1.0 Universal (Public Domain Dedication)

What we use:

  • Current and historical legislator biographical data (name, birthday, gender)
  • Party affiliation and state representation
  • Term start and end dates for every Congress
  • Committee and subcommittee assignments with leadership roles
  • Social media accounts (Twitter, Facebook, YouTube, etc.)
  • Official website URLs
  • Bioguide, Thomas, FEC, GovTrack, ICPSR, and other cross-reference IDs

Coverage: All current members of the 119th Congress (100 senators, 435 representatives, plus non-voting delegates)

Update frequency: Maintained by the open-source community and updated regularly as changes occur (new members sworn in, committee reassignments, etc.)

Methodology: This is a collaboratively maintained dataset hosted on GitHub. Contributors submit pull requests when congressional membership or committee assignments change. The data is stored in structured YAML files and is considered the most comprehensive freely available source of legislator metadata.

unitedstates/images

Repository: github.com/unitedstates/images

License: CC0 1.0 Universal (Public Domain Dedication)

What we use:

  • Official legislator photographs (original and multiple thumbnail sizes)
  • Images keyed by Bioguide ID for reliable matching

Coverage: Photographs for the vast majority of current and recent members of Congress

Update frequency: Updated as new official photos become available, typically at the start of each new Congress or when members are newly elected

Methodology: Images are sourced from official congressional portrait galleries and government publications. They are stored in standardized sizes (original, 450px, 225px) and organized by Bioguide ID, making them straightforward to match to legislator records.

OpenSourceActivismTech/us-zipcodes-congress

Repository: github.com/OpenSourceActivismTech/us-zipcodes-congress

What we use:

  • ZIP code to congressional district mapping
  • Enables the “Find My Rep” lookup feature

Coverage: All U.S. ZIP codes mapped to their corresponding congressional districts

Update frequency: Updated following redistricting cycles and as ZIP code boundaries change

Methodology: This dataset maps U.S. ZIP codes to congressional districts using geographic intersection data. Because ZIP codes do not align perfectly with district boundaries, some ZIP codes may map to multiple congressional districts. Our lookup tool accounts for this by returning all possible representatives for a given ZIP code.

Congress.gov API v3

Website: api.congress.gov

License: Free to use; API key required (no cost)

What we use (Phase 2):

  • Bill data (sponsor, cosponsors, status, text)
  • Roll call votes and voting records
  • Floor actions and legislative activity
  • Committee hearing schedules

Coverage: Congressional activity from the 93rd Congress (1973) to the present

Update frequency: Near real-time updates as legislative actions occur

Methodology: The Congress.gov API is the official API of the Library of Congress, providing structured access to legislative data. Data is sourced from the Government Publishing Office (GPO), the Clerk of the House, and the Secretary of the Senate. We will integrate this data in Phase 2 to add voting records and bill tracking to legislator profiles.

U.S. Census Bureau

Website: census.gov

What we use:

  • State and district population data
  • Geographic boundary data for congressional districts

Coverage: All 50 states, the District of Columbia, and U.S. territories

Update frequency: Decennial census with annual population estimates

Methodology: Population figures are drawn from the American Community Survey and decennial census data. Congressional district boundaries are based on the most recent redistricting following the 2020 Census.

Data Processing

How We Build Pages

  1. Fetch — Automated scripts pull data from GitHub repositories and APIs
  2. Process — A processing pipeline normalizes, validates, and merges data across sources (legislator records, committee assignments, images, and ZIP code mappings)
  3. Generate — Processed data is written to Hugo data files (JSON) and content page frontmatter (YAML)
  4. Build — Hugo generates static HTML pages for every legislator, committee, state, and district

Data Quality

  • Legislator records are cross-referenced across multiple ID systems (Bioguide, GovTrack, FEC) to ensure accuracy
  • Missing values are displayed as unavailable rather than interpolated
  • Committee assignments are validated against official congressional records
  • ZIP code lookups handle multi-district ZIP codes by returning all possible matches

Data Refresh

Our data pipeline runs on a regular schedule to capture changes in congressional membership, committee assignments, and other updates. Because the underlying data sources are community-maintained and government-published, changes are typically reflected within a few days of occurring.

Known Limitations

  • ZIP code precision — Some ZIP codes span multiple congressional districts. Our lookup returns all possible matches, but users in split-ZIP areas may need to verify their exact district using their full street address.
  • Redistricting lag — Following redistricting, it takes time for all data sources to update. District boundaries shown may briefly lag behind official changes.
  • Photo availability — Not every legislator has a publicly available official photograph. Newly elected members may temporarily lack photos until official portraits are released.
  • Committee changes — Committee assignments can change throughout a congressional session. There may be a brief delay between official reassignments and our data reflecting the change.
  • Phase 2 data — Bill tracking, voting records, and floor actions from the Congress.gov API are planned features and are not yet available on the site.

Citing KingSt.com

If you use KingSt.com data in a publication or report, we suggest the following citation:

KingSt.com. Federal Congressional Tracker. kingst.com. Accessed [date].

For the underlying data, please cite the original source (unitedstates/congress-legislators, Congress.gov, or Census Bureau) as appropriate.

Questions

If you have questions about our data or methodology, please contact us.