Access data via the Application Programming Interface API
The U.S. Census Bureau provides a comprehensive API (Application Programming Interface) that allows developers and researchers to access a vast array of demographic, economic, and social data. This is an efficient way to integrate Census data into applications, research, or custom analyses.
Here's a breakdown of key aspects of the Census API:
1. What is the Census API? The Census API is a data service that provides public access to raw statistical data from various Census Bureau data programs. It allows users to make structured requests for specific data variables and geographies.
2. Available Data Sets The API provides access to data from numerous surveys and programs, including:
| • | American Community Survey (ACS): 1-year, 3-year (discontinued), and 5-year data covering a broad range of social, economic, demographic, and housing characteristics. This is one of the most frequently used datasets. |
| • | Decennial Census: Data from the 2000, 2010, and 2020 Censuses, providing population and housing information down to the highest geographic resolution (e.g., block group). |
| • | Economic Census: Data on various sectors of the U.S. economy. |
| • | County Business Patterns (CBP) and ZIP Code Business Patterns (ZBP): Subnational economic data by industry. |
| • | Population Estimates and Projections. |
| • | Annual Business Survey (ABS) and Nonemployer Statistics by Demographics (NES-D). |
| • | Geocoding Services: Allows for converting addresses to latitude/longitude coordinates and associated Census geographies. |
| • | TIGERweb GeoServices REST API: Provides Census area boundaries/shapes referenced by FIPS codes. |
You can explore the full list of available APIs and datasets on the Census Bureau's Developers website.
3. How to Access and Use the API:
| • | API Key: While you can make up to 500 queries per IP address per day without an API key, you will need to register for a free API key if you plan to make more frequent requests (over 500 per day) or if you are developing a web or mobile application. The key is appended to your API call URL. |
| o | To request a key, visit the Census Bureau Developers site and click "Request a KEY." |
| • | API Call Structure: API calls are typically made via HTTP GET requests. The URL structure generally includes: |
| o | Host Name: https://api.census.gov/data |
| o | Year: The vintage (reference year) of the data. |
| o | Dataset Acronym: e.g., acs/acs5 for ACS 5-year data. |
| o | Variables: A list of the specific data variables you want to retrieve. |
| o | Geography: Specifies the geographic level (e.g., state, county, tract) and specific codes (FIPS codes) for the desired locations. |
| o | API Key (if needed): &key=YOUR_KEY_HERE |
| • | Documentation and User Guides: The Census Bureau provides extensive documentation and user guides to help developers: |
| o | Census Data API User Guide: Explains how to use the API to request data, covers core concepts, and provides example queries. |
| o | Census Microdata API User Guide: Focuses on accessing microdata. |
| o | Video Tutorials and Webinars: The Census Academy offers various resources, including webinars and video tutorials, to guide users through the API basics and more advanced topics. |
| o | Dataset Discovery Tool: Helps you find available datasets. |
| • | Programming Languages and Tools: |
| o | The API can be accessed using various programming languages (e.g., Python, R, JavaScript) by constructing the appropriate URL and making an HTTP request. |
| o | Libraries like tidycensus (for R) and censusapi (for R) simplify the process of interacting with the Census API. |
4. Key Concepts:
| • | Variables: These are the specific data points you want to retrieve (e.g., total population, median income, housing units). Each dataset has its own set of variable codes. |
| • | Geography: Data is typically associated with specific Census geographic boundaries, identified by FIPS codes. You can request data at various levels, from the national level down to block groups. |
| • | Vintage: Refers to the year of the data. |
5. Support and Community: The Census Bureau provides a Developers' Forum (often on Slack) where users can ask questions, share applications, and provide feedback. You can also contact them via email at census.data@census.gov for assistance.
By utilizing the Census API, you can programmatically access and integrate a wealth of valuable demographic and economic data into your projects.
