Census Data API User Guide
The purpose of this user guide is to instruct developers and researchers on how to use the Census Data Application Programming Interface (API) to request data from U.S. Census Bureau datasets.
Query Limits
Query Limits
You can include up to 50 variables in a single API query. An API key must be used with all queries made to the Census Data API. The API key is a security measure that protects both the Census Bureau and data users. The key will be part of your data request URL string.
Related Information
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How-to Materials for Using the Census APIDo you have questions on how to use the Census API? Check out our step-by-step guidance to learn how to use the Census API to find the data you need.
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Data ToolExplore Census DataThis new platform on data.census.gov is based on overwhelming feedback to streamline the way you get data and digital content from Census Bureau.
Page Last Revised - May 14, 2026