committees

Historical committee membership data from @unitedstates project committee-membership-current.yaml version history

A minimal version of combined data described below, including committee membership and leadership positions, is in the data folder:

data/members_committees_combined.rda

More detailed versions of these data can be reproduced with the code in this repository:

• download_committee_membership_versions.sh collects yaml files from the version history of committee-membership-current.yaml

• combine_yaml.R combines them into a single historical committee membership dataset.

• make_members_committees.R merges in other legislator and committee data from the @unitedstates project

  • legislators-historical.csv
  • committees-historical.csv

It also completes missing ICPSR IDs using the legislators R package

• make_stewart_woon_committees_membership_103-115 merges data from from Stewart and Woon, making a number of corrections https://web.mit.edu/17.251/www/data_page.html

• merge_committees.R merges the two above sources

• make_oversight_committee_data.R merges this with Lewis and Selin's ACUS oversight jurisdiction data https://www.vanderbilt.edu/csdi/sourcebook.php

This README describes the workflow, data, and requested citation.

Committee Membership Historical Snapshots from @united-states/legislators

This project creates a historical record of U.S. congressional committee membership using archived versions of the committee-membership-current.yaml file from the unitedstates/congress-legislators GitHub repository.

The workflow has two main steps:

1. Download historical versions of the YAML file from Git history.
2. Combine those YAML snapshots into a single tabular dataset.

Scripts

download_committee_membership_versions.sh

Downloads every committed version of:

committee-membership-current.yaml

from the GitHub repository:

https://github.com/unitedstates/congress-legislators

The script uses git log to identify commits that modified the file and git show to save the version of the file at each commit.

Usage

From the project directory, run:

bash download_committee_membership_versions.sh

Output

The script creates a directory:

committee-membership-versions/

and saves one YAML file per Git commit.

Example output files:

committee-membership-versions/
  committee-membership-2019-03-28-a1b2c3d.yaml
  committee-membership-2020-12-07-e4f5g6h.yaml
  committee-membership-2021-03-03-b9ef418.yaml

Each filename includes:

• the commit date, in YYYY-MM-DD format
• the short Git commit SHA

---

combine_yaml.R

Reads the downloaded YAML snapshot files and combines them into a single historical committee membership dataset.

The script:

• finds all saved committee membership YAML files
• extracts the snapshot date from each filename
• calculates the Congress number from the snapshot date
• reads committee membership data from each YAML file
• adds source metadata such as the filename and path
• combines all valid snapshots into one data frame
• skips malformed YAML files when they cannot be read

Some historical snapshots contain YAML formatting problems, such as duplicate map keys. These files are skipped because there are many available snapshots and the project does not require every single version.

Usage

Run the script from R or RStudio:

source("combine_yaml.R")

or from the command line:

Rscript combine_yaml.R

Main output

The main object created by the script is:

membership_snapshots

This is a combined data frame with one row per observed committee membership in a given snapshot.

Important columns include:

Column	Description
snapshot_date	Date of the Git commit, extracted from the YAML filename
congress	Congress number inferred from snapshot_date
source_file	Name of the YAML file used for that observation
source_path	Full path to the YAML file
thomas_id	Committee identifier from the YAML structure
bioguide_id	Member Bioguide ID, renamed from bioguide when present
other columns	Additional fields from the original YAML data, such as name, party, rank, or title when available

Data created

Raw YAML snapshots

Directory:

committee-membership-versions/

or, depending on local configuration:

data/committee-membership-versions/

These files are direct exports of historical versions of committee-membership-current.yaml from GitHub.

Example:

committee-membership-2021-03-03-b9ef418.yaml

The date in the filename is used as the snapshot date. The short SHA identifies the exact Git commit.

---

Combined membership snapshots

The combined dataset contains committee membership observations stacked across all readable snapshots.

data/membership_snapshots.rda

Merge in committee names and legislator metadata + complete missing ICPSR ids

code/make_members_committees.r

• merges committee codes with committee names from committees-current.yaml
• merges bioguide IDs with member names and other information in legislators-historical.csv
• completes missing ICPSR IDs using the legislators package https://github.com/judgelord/legislators to get ICPSRs from the "full_name"

The combined data include member-congress observations of merged info on members and their committees.

"data/members_committees.rda"

Merge with Stewart and Woon historical committee data

code/make_stewart_woon_committees.R makes several hundred corrections to the Stewart and Woon data.^[Charles Stewart III and Jonathan Woon. Congressional Committee Assignments, 103rd to 114th Congresses, 1993--2017: House of Representatives, 2017]

These data are made available for academic use, but may not be used commercially.

code/merge_committees.R merges @unitedstates and Stewart and Woon data.

The combined data include committee membership and leadership positions.

The minimal version of those data is:

data/members_committees_combined.rda

Citation

Because they are a composite, these data require at least three citations:

1. Devin Judge-Lord. 2026. "Congressional Committee Assignments and Leadership Positions, 103th to 119th Congresses, 1993--2026"

2. Charles Stewart III and Jonathan Woon. 2017. "Congressional Committee Assignments, 103rd to 114th Congresses, 1993--2017"

3. @unitedstates-project, 2026. “Unitedstates/Congress-Legislators.” https://github.com/unitedstates/congress-legislators. Date Accessed: June 19, 2026.

If you are using code to pull in additional variables from Lewis and Selin (2012) or voteview.com, you should cite them as well.

References

Devin Judge-Lord, Eleanor Neff Powell, and Justin Grimmer. 2025. “The Effects of Shifting Priorities and Capacity on Elected Officials’ Policy Work and Constituency Service: Evidence from a Census of Legislator Requests to U.S. Federal Agencies, Replication Data.” American Journal of Political Science. Harvard Dataverse Network, at: https://doi.org/10.7910/DVN/LWOCW.

Lewis, David E., and Jennifer L. Selin. 2012. ACUS Sourcebook of United States Executive Agencies. Administrative Conference of the United States.

Lewis, Jeffrey B., Keith Poole, Howard Rosenthal, Adam Boche, Aaron Rudkin, and Luke Sonnet. 2026. “Voteview: Congressional Roll-Call Votes Database.” https://voteview.com. Date Accessed: June 19, 2026.

Stewart, Charles III, and Jonathan Woon. 2017. “Congressional Committee Assignments, 103rd to 115th Congresses, 1993–2017: House of Representatives.” https://web.mit.edu/17.251/www/data_page.html#2. Date Accessed: March 18, 2025.

@unitedstates-project, the. 2026. “Unitedstates/Congress-Legislators.” https://unitedstates.github.io/ https://github.com/unitedstates/congress-legislators. Date Accessed: June 19, 2026.