IPUMS Microdata API

Overview

IPUMS (Integrated Public Use Microdata Series) provides the world's largest collection of harmonized census and survey microdata. Hosted by the University of Minnesota, it covers demographic, health, labor, and geographic data across 100+ countries and 100+ years. The API enables programmatic extract creation, metadata queries, and data retrieval. Free registration required.

IPUMS Data Collections

Collection	Coverage	Records
IPUMS USA	U.S. Census & ACS (1850-present)	16B+ person-records
IPUMS CPS	Current Population Survey (1962-present)	Labor force data
IPUMS International	Census data from 100+ countries	2B+ person-records
IPUMS NHGIS	U.S. geographic/aggregate data	County-level stats
IPUMS DHS	Demographic and Health Surveys	300+ surveys, 90 countries
IPUMS Time Use	American Time Use Survey	Time diary data
IPUMS Health	NHIS health surveys	Health/disability data
IPUMS Higher Ed	NSCG/SDR science workforce	S&E workforce data

API Endpoints

Base URL

https://api.ipums.org/extracts/

Authentication

# Register at https://www.ipums.org/
# API key from your account settings
export IPUMS_KEY="..."

Create an Extract

# Request a data extract (IPUMS USA example)
curl -X POST "https://api.ipums.org/extracts/?collection=usa&version=2" \
  -H "Authorization: $IPUMS_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "description": "Income by education, 2020 ACS",
    "data_structure": {"rectangular": {"on": "P"}},
    "data_format": "csv",
    "samples": {"us2020a": {}},
    "variables": {
      "AGE": {},
      "SEX": {},
      "RACE": {},
      "EDUC": {},
      "INCTOT": {},
      "EMPSTAT": {}
    }
  }'

Check Extract Status

curl "https://api.ipums.org/extracts/42?collection=usa&version=2" \
  -H "Authorization: $IPUMS_KEY"

Download Extract

# When status is "completed"
curl -O "https://api.ipums.org/extracts/42/download?collection=usa&version=2" \
  -H "Authorization: $IPUMS_KEY"

Query Metadata

# List available variables
curl "https://api.ipums.org/metadata/usa/variables?version=2" \
  -H "Authorization: $IPUMS_KEY"

# Get variable details
curl "https://api.ipums.org/metadata/usa/variables/EDUC?version=2" \
  -H "Authorization: $IPUMS_KEY"

# List available samples
curl "https://api.ipums.org/metadata/usa/samples?version=2" \
  -H "Authorization: $IPUMS_KEY"

Python Usage

import os
import time
import requests

BASE_URL = "https://api.ipums.org"
HEADERS = {"Authorization": os.environ.get("IPUMS_KEY", "")}


def create_extract(collection: str, samples: dict,
                   variables: list, description: str = "",
                   data_format: str = "csv") -> int:
    """Create an IPUMS data extract request."""
    var_dict = {v: {} for v in variables}
    body = {
        "description": description,
        "data_format": data_format,
        "data_structure": {"rectangular": {"on": "P"}},
        "samples": {s: {} for s in samples} if isinstance(samples, list)
                   else samples,
        "variables": var_dict,
    }

    resp = requests.post(
        f"{BASE_URL}/extracts/?collection={collection}&version=2",
        headers={**HEADERS, "Content-Type": "application/json"},
        json=body,
    )
    resp.raise_for_status()
    return resp.json()["number"]


def wait_for_extract(extract_id: int, collection: str,
                     poll_interval: int = 30) -> str:
    """Poll until extract is ready, return download URL."""
    while True:
        resp = requests.get(
            f"{BASE_URL}/extracts/{extract_id}"
            f"?collection={collection}&version=2",
            headers=HEADERS,
        )
        resp.raise_for_status()
        data = resp.json()
        status = data.get("status")

        if status == "completed":
            return data["download_links"]["data"]["url"]
        elif status == "failed":
            raise RuntimeError(f"Extract failed: {data}")
        print(f"Status: {status}, waiting {poll_interval}s...")
        time.sleep(poll_interval)


def get_variable_info(collection: str, variable: str) -> dict:
    """Get metadata about a variable."""
    resp = requests.get(
        f"{BASE_URL}/metadata/{collection}/variables/{variable}"
        f"?version=2",
        headers=HEADERS,
    )
    resp.raise_for_status()
    return resp.json()


# Example: request 2020 ACS income data
extract_id = create_extract(
    collection="usa",
    samples=["us2020a"],
    variables=["AGE", "SEX", "RACE", "EDUC", "INCTOT", "EMPSTAT"],
    description="Education-income analysis 2020",
)
print(f"Extract #{extract_id} submitted. Waiting...")

download_url = wait_for_extract(extract_id, "usa")
print(f"Ready: {download_url}")

Key Variables (IPUMS USA)

Variable	Description
AGE	Age
SEX	Sex
RACE	Race
EDUC	Education level
INCTOT	Total income
EMPSTAT	Employment status
OCC	Occupation
IND	Industry
POVERTY	Poverty status
MIGRATE1	Migration status
MARST	Marital status
NCHILD	Number of children

Use Cases

1. Demographic research: Population trends, migration, aging
2. Labor economics: Wage gaps, employment patterns, occupation shifts
3. Health disparities: Insurance coverage, disability, access to care
4. Education research: Educational attainment trends, returns to education
5. Historical analysis: Long-run comparisons using harmonized variables

References

• IPUMS
• IPUMS API Documentation
• IPUMS USA
• Ruggles, S. et al. (2024). "IPUMS USA: Version 15.0." Minneapolis: IPUMS.