Load ProPublica Congress API data to DuckDB

The ProPublica Congress API provided programmatic access to legislative data from the U.S. House, Senate, and Library of Congress. Everything needed to build a working ProPublica Congress API → DuckDB pipeline is on this page: the API's base URL, authentication, endpoints, pagination and incremental field — plus a prompt that hands the whole job to your coding agent.

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Build your ProPublica Congress API to DuckDB pipeline

Paste this prompt into Claude, Codex, or Cursor. The agent does the rest.

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Run uvx dlthub-init@latest to build a pipeline from ProPublica Congress API to DuckDB and run it on dltHub

That scaffolds a dltHub workspace and installs the dltHub AI harness — the project rules, the secrets-management skill, and the dlt MCP server your agent needs to work safely. From there it reads the ProPublica Congress API API, proposes the endpoints to load, then writes, runs and validates the pipeline while you review rather than type. Credentials are inspected through MCP tools, so your agent never reads secrets.toml itself. How the LLM-native workflow works →

Prefer to write it yourself? Every fact the agent uses is below.

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ProPublica Congress API API at a glance

These values come from the ProPublica Congress API API reference — the authoritative source if anything here looks out of date.

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How do I authenticate with the ProPublica Congress API API?

Authentication is performed by passing the API key as a custom request header named X-API-Key.

1. Get your credentials

The ProPublica Congress API is no longer available and is currently maintained only as a historical reference. ProPublica officially states that new API keys are no longer being issued or supported. Consequently, there is no active dashboard or registration process for obtaining credentials.

2. Add them to .dlt/secrets.toml

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[sources.propublica_congress_api_source]
# Note: This API is deprecated and no longer functional. # X-API-Key is the header used in historical implementations.
x_api_key = "your_deprecated_api_key_here"

dlt reads this file automatically at runtime. With the harness, the setup-secrets skill prompts you for the values and never handles the raw credential in chat. For production, see setting up credentials with dlt.

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What ProPublica Congress API data can I load into DuckDB?

These are the ProPublica Congress API endpoints dlt can load into DuckDB:

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How do I load only new ProPublica Congress API records?

The ProPublica Congress API API reference does not document a timestamp or sequence field for these endpoints, so there is nothing to advertise here as verified. Pick a field from the endpoints table above that increases with every write, then set it as the cursor_path.

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{"name": "votes_recent", "endpoint": {
    "path": "house/votes/recent.json",
    # Replace with a field that increases on every write.
    "incremental": {"cursor_path": "REPLACE_ME", "initial_value": "2024-01-01T00:00:00Z"},
}}

On the first run dlt loads everything from initial_value; on every run after that it requests only what changed and appends with write_disposition="merge" if you set a primary key. See incremental loading.

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What does the generated ProPublica Congress API pipeline look like?

A standard dlt REST API pipeline — the same code you would write by hand, loading votes/recent and members from the ProPublica Congress API API into DuckDB:

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import dlt
from dlt.sources.rest_api import RESTAPIConfig, rest_api_resources

@dlt.source
def propublica_congress_api_source(api_key=dlt.secrets.value):
    config: RESTAPIConfig = {
        "client": {
            "base_url": "https://api.propublica.org/congress/v1",
            "auth": {"type": "api_key", "api_key": api_key, "name": "X-API-Key", "location": "header"},
        },
        "resources": [
            {"name": "votes_recent", "endpoint": {"path": "house/votes/recent.json", "data_selector": "results"}},
            {"name": "bill_search", "endpoint": {"path": "bills/search.json", "data_selector": "results"}}
        ],
    }
    yield from rest_api_resources(config)


def load_propublica_congress_api_to_duckdb() -> None:
    pipeline = dlt.pipeline(
        pipeline_name="propublica_congress_api_pipeline",
        destination="duckdb",
        dataset_name="propublica_congress_api_data",
    )
    load_info = pipeline.run(propublica_congress_api_source())
    print(load_info)


if __name__ == "__main__":
    load_propublica_congress_api_to_duckdb()

Run it with python propublica_congress_api_pipeline.py. The agent iterates on this until it loads cleanly — you review and approve, rather than write it from scratch.

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How do I query ProPublica Congress API data in DuckDB?

dlt creates one table per resource. Query the loaded data with Python or SQL — or ask your agent to, through the MCP server's execute_sql_query tool.

Python (pandas DataFrame):

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import dlt

data = dlt.pipeline("propublica_congress_api_pipeline").dataset()
df = data.votes_recent.df()
print(df.head())

SQL:

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SELECT * FROM propublica_congress_api_data.votes_recent LIMIT 10;

See querying your data with dataset and exploring it in marimo notebooks.

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How do I deploy the ProPublica Congress API to DuckDB pipeline in production?

The pipeline runs locally, which is ideal for prototyping and one-off analysis. When you need it on a schedule, monitored on every load, and shared with your team, deploy the same dlt code on the dltHub platform — no infrastructure to maintain. The prompt above already ends with "run it on dltHub", so your agent can take it there directly.

• Deploy & schedule — run the pipeline as a managed job with automatic retries.
• Monitor — observable job queues, alerting, and load metrics for every run.
• Transform — promote raw ProPublica Congress API loads into governed, documented models.
• Visualize & share — explore data in notebooks and publish live dashboards instead of static screenshots.

Book a demo →

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What other destinations can I load ProPublica Congress API data to?

dlt loads into any of these — only the destination argument changes:

Set dlt.pipeline(destination="snowflake") and add credentials in .dlt/secrets.toml. On the dltHub platform the same pipeline runs against a managed Iceberg lakehouse. See the full destinations list.

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Next steps

• Ready for production? Book a demo of the dltHub platform →
• dlt LLM-native workflow docs
• REST API source reference
• Join the dlt community on Slack