Definition
The Common Core of Data (CCD) is the primary database on public elementary and secondary education in the United States, maintained by the National Center for Education Statistics (NCES). Every year, state education agencies compile and submit administrative records for all public schools, districts, and state agencies. These records are then processed and published by NCES.
How K12 Atlas uses it
K12 Atlas uses CCD as the core architectural skeleton of the school dataset. Every school profile is keyed by its unique NCES ID (combokey). Basic directory attributes—such as the school's official name, street address, mailing address, county, phone number, grades served (span), and locale classification (urban, suburban, town, rural)—come directly from the CCD database.
Source caveats
Because the CCD relies on reports from 50+ different state education departments, data definitions can occasionally vary. For instance, pupil-teacher ratios and teacher counts (FTE) may reflect slightly different certification rules between states. Furthermore, NCES typically publishes the finalized CCD directory on a 1-to-2 year lag, meaning K12 Atlas reconciles the latest available CCD release with current-year state updates.
Implementation rule
In the K12 Atlas data engine, CCD directory fields are treated as the lowest-common-denominator fallback. If a state agency publishes an updated active school list or revised enrollment counts for the current year, the data pipeline overlays the state-specific values while keeping the historical NCES ID and geographic coordinates.
Organic role
This page serves to explain the structural baseline of our school records. From this definition, researchers can explore data stories concerning multi-year enrollment shifts, examine school district boundary definitions, or download sample data sheets for a specific district.
What not to infer
A CCD registration does not indicate academic quality or school performance. It is an administrative census showing that a public school exists, is funded by taxpayers, and has reported basic enrollment numbers. K12 Atlas does not construct rating scores or editorial evaluations from CCD directory rows.
Related buyer path
For users who need national directory files, state slices, or district-level Excel reports containing NCES IDs, addresses, and enrollment breakdowns, K12 Atlas provides free sample sheets (such as the Austin ISD sample) and paid packages covering all 102,176 public schools.