How we calculate the numbers — and why you should trust them
Every score on this site comes from official government records. Here is exactly how we calculate what you see — no black boxes, no editorial judgment.
Data Sources
All congressional data is sourced exclusively from official U.S. government APIs. No third-party political databases or opinion sources are used.
- Bill text, status, and history: Congress.gov API (Library of Congress)
- Member biographies and committee assignments: Congress.gov API
- Sponsorship and co-sponsorship records: Congress.gov API
- House roll call votes (103rd–119th, 1993–present): House Clerk XML files (clerk.house.gov)
- Senate roll call votes (100th–119th, 1987–present): Voteview.com (UCLA Political Science — academic dataset sourced from official Senate records)
- Campaign finance contributions (2014–present, 113th Congress onward): FEC.gov API (Federal Election Commission)
- Plain-English summaries: Claude AI (Anthropic), generated via automated pipeline
Data coverage notes: Bill and member data covers the 93rd Congress (1973) onward, with the exception of the 94th–98th Congresses (1975–1985) which have not yet been imported. Roll call vote records begin with the 100th Congress for the Senate and the 103rd Congress for the House. Campaign finance data covers election cycles 2014–2026. Earlier FEC records exist and may be added in a future update.
Effectiveness Score
The effectiveness score is a composite of four equally transparent metrics. No subjective judgment is applied. The formula is fixed and applied identically to every Congress.
The percentage of introduced bills that were ultimately signed into law. A higher ratio indicates a more legislatively productive Congress.
The percentage of floor votes where members of both parties voted the same direction. Higher bipartisan agreement indicates cross-party cooperation.
The percentage of scheduled working days that Congress was actually in session, versus in recess or adjourned.
Whether annual appropriations bills were signed into law before the October 1 fiscal year deadline. Continuing resolutions and government shutdowns reduce this score.
How We Calculate Bipartisan Cooperation
A vote is counted as bipartisan when a majority of Republican members and a majority of Democratic members voted on the same side (both majority Yea, or both majority Nay). Only contested votes where both parties had at least 5 members voting are included — procedural near-unanimous votes are filtered to reflect genuine cooperation.
House Clerk roll call XML files (clerk.house.gov). Each XML file contains individual member votes by bioguide ID.
Voteview.com academic roll-call dataset (UCLA Political Science). Voteview sources from official Senate records and is the authoritative academic database for congressional votes.
House and Senate bipartisan rates are displayed separately on each Congress scorecard page. The combined score used in the effectiveness formula is the average of both chambers when both are available, or the single chamber's rate when only one is available.
Why some Congresses show estimates instead of computed vote data
For the 93rd–99th Congresses (1973–1987), no machine-readable roll call records exist in the sources we use. House Clerk XML files begin with the 103rd Congress (1993). The Voteview academic dataset begins with the 100th Congress (1987). For these earlier Congresses, bipartisan figures are sourced from CRS congressional research studies and GovTrack historical analyses, clearly labelled as estimates on the scorecard page. For the 94th–98th Congresses, bill data has not yet been imported from Congress.gov — these records exist in the source database and will be added in a future update.
AI-Generated Summaries
Plain-English bill summaries are generated by Claude (Anthropic) using a structured, non-partisan prompt. The prompt instructs the model to:
- Describe what the bill actually does in plain language
- Identify who would be affected and how
- Note any changes to existing law
- Avoid political framing, endorsement, or opinion
- Flag if the bill name does not accurately describe its contents
Summaries are generated once per bill via an automated nightly pipeline and stored statically. They are not generated in real time per visitor. The AI does not have access to polling data, political commentary, or opinion sources during generation.
Why some bills have no summary
A summary can only be generated if the sponsor uploaded the bill's legislative text to Congress.gov. Many bills — especially those introduced but not advanced — never have text uploaded. When no text is available, our system displays a notice rather than attempting to summarize from the title alone. The bill still appears in our database with all other available information (sponsor, status, policy area, vote history). This is a limitation of the source data, not of our pipeline.
Editorial Policy
Congress-Decoded has no editorial staff making political judgments. The site does not endorse any candidate, party, or political position. Every data point is sourced from official government records and displayed without commentary.
If you find an error in the data, it reflects an error in the underlying Congress.gov record. Links to source documents are provided on every page so you can verify the data yourself.