| name | education-data-source-ccd |
| description | CCD — federal universe of all U.S. public K-12 schools (~100K) and districts (~18K). Enrollment, staffing, finance, directory data (1986-present). Use for public school analysis by grade/race/sex. Public only; excludes private and postsecondary. |
| metadata | {"audience":"any-agent","domain":"data-source","skill-authored":"2026-02-09","skill-last-updated":"2026-08-06"} |
CCD Data Source Reference
Common Core of Data (CCD) — the federal complete-universe database of all U.S. public K-12 schools and districts (~100,000 schools, ~18,000 districts), collecting enrollment, staffing, finance, and directory data annually (1986-present). Use when analyzing public school enrollment by grade/race/sex, district finances, school staffing, or directory attributes. Public schools and districts only; excludes private schools and postsecondary. Note significant variable encoding and race/ethnicity definition changes over time.
The CCD is the Department of Education's comprehensive, annual, national database of all public elementary and secondary schools and school districts in the United States. It is the only federal dataset that provides a complete universe census (not a sample) of U.S. public K-12 education.
CRITICAL: Value Encoding
The Education Data Portal uses integer codes for categorical variables that
differ from NCES's original string codes. Always verify codes against codebooks.
| Context | school_type | charter | urban_centric_locale |
|---|
| Portal (integers) | 1 (Regular) | 0 (No) / 1 (Yes) | 11 (City-Large) |
| NCES original | 1-Regular school | Yes / No | 11-City: Large |
Note: charter and magnet use 0/1 encoding, NOT 1=Yes / 2=No as some NCES documentation shows.
See ./references/variable-definitions.md for complete encoding tables.
What is CCD?
- Primary K-12 database: DOE's authoritative source for public elementary/secondary education statistics
- Universe survey: Covers ALL public schools and districts, not a sample
- Annual collection: Data submitted by State Education Agencies (SEAs) each year
- Six major components: Directory, Membership, Staffing, Finance (state and district), Dropout/Completers
- Coverage: ~100,000 public schools and ~18,000 school districts nationwide
- Historical depth: Data available from 1986 to present (varies by component)
- Collector: National Center for Education Statistics (NCES) via EDFacts
- Mirror coverage (v2 build validated 2026-08-06): Five bulk dataset families; the current versioned mirror (Portal v0.26.1) carries CCD content spanning 1986-2024, with directory and enrollment reaching the 2023-24 school year (file year 2024) while district finance remains at 2020. Mirror publication differs by surface; see Data Access.
Reference File Structure
| File | Purpose | When to Read |
|---|
survey-components.md | Detailed coverage of each CCD survey component | Understanding what data is collected |
data-collection.md | How data flows from schools to NCES, timelines, respondent universe | Understanding data provenance and timing |
variable-definitions.md | Key variables, coding schemes, special values | Interpreting specific data elements |
data-quality.md | Missing data patterns, suppression, state variations | Assessing data reliability |
historical-changes.md | Definition changes, code revisions over time | Longitudinal analysis |
Decision Trees
What CCD component do I need?
What information do you need?
├─ School/district names, addresses, contacts → Directory
│ └─ See ./references/survey-components.md#directory
├─ Student enrollment counts → Membership
│ ├─ By grade → Membership (grade disaggregation)
│ ├─ By race/ethnicity → Membership (race disaggregation)
│ ├─ By sex → Membership (sex disaggregation)
│ └─ See ./references/survey-components.md#membership
├─ Staff/teacher counts → Staffing
│ └─ See ./references/survey-components.md#staffing
├─ Revenue and expenditure → Finance
│ ├─ State-level totals → National Public Education Financial Survey
│ ├─ District-level detail → School District Finance Survey (F-33)
│ └─ See ./references/survey-components.md#finance
├─ Graduation/dropout rates → Dropout and Completers
│ └─ See ./references/survey-components.md#dropout-completers
└─ School type, charter status, locale → Directory
└─ See ./references/survey-components.md#directory
Is this a data quality issue?
Unexpected data values?
├─ Negative numbers (-1, -2, -3, -9) → Missing data codes
│ └─ See ./references/variable-definitions.md#missing-data-codes
├─ Very different from prior year → Check for definition changes
│ └─ See ./references/historical-changes.md
├─ State appears as outlier → Check state-specific reporting
│ └─ See ./references/data-quality.md#state-variations
├─ Large number of zeros → Check suppression rules
│ └─ See ./references/data-quality.md#suppression
└─ Locale codes don't match → Pre/post 2006 locale system change
└─ See ./references/historical-changes.md#locale-codes
Can I compare across time?
Building a time series?
├─ Race/ethnicity categories → Major change in 2010
│ └─ See ./references/historical-changes.md#race-ethnicity
├─ Locale codes → Completely revised in 2006
│ └─ See ./references/historical-changes.md#locale-codes
├─ School/district IDs → Check for ID changes
│ └─ See ./references/variable-definitions.md#identifiers
├─ Free/reduced lunch → CEP and direct certification changes
│ └─ See ./references/data-quality.md#frpl
└─ Finance data → Definition changes and inflation
└─ See ./references/historical-changes.md#finance
Quick Reference: CCD Components
| Component | Level | Key Variables | Years | Update Cycle |
|---|
| Directory | School, LEA, State | Name, address, type, status, locale, charter | 1986+ | Annual |
| Membership | School, LEA, State | Enrollment by grade, race, sex | 1986+ | Annual |
| Staffing | School, LEA, State | FTE teachers, staff by category | 1987+ | Annual |
| Finance (State) | State | Revenue, expenditure by source/function | 1989+ | Annual (1-2 yr lag) |
| Finance (District) | LEA | Revenue, expenditure, per-pupil | 1989+ | Annual (2 yr lag) |
| Dropout/Completers | LEA, State | Dropout counts, diploma recipients | 1991+ | Annual |
Note: Not all components listed above are available through the Portal mirrors. See the Data Access section for which datasets are mirrored.
Key Identifiers
| Portal Column | Format | Level | Example | Notes |
|---|
ncessch | 12 characters | School | 010000100100 | State FIPS (2) + LEA suffix (5) + School (5) |
leaid | 7 characters | District | 0100001 | State FIPS (2) + State-assigned (5) |
fips | 2 digits | State | 01 | Federal Information Processing Standard |
Identifier-width requirement (an analysis-time normalization contract, not a raw-file guarantee):
Treat ncessch and leaid as identifiers, not quantities. At analysis time, validate
nonmissing, nonsentinel ncessch as a numeric string of exactly 12 characters and leaid as a
numeric string of exactly 7 characters before joining.
The current v2 mirror (validated 2026-08-06) has no universal identifier contract — per-file
id typing is heterogeneous, so this width rule describes how you must normalize on read, not
what the raw files contain. Observed reality: leaid is native-width String (including
alphanumeric values such as 06D0004, widths 2-7) in districts_ccd_finance, but Int64 in
school-districts_lea_directory and districts_saipe. Integer storage cannot preserve leading
zeros or display-width semantics, so an Int64 leaid/ncessch must be cast to a zero-padded
string before width validation. Inspect the actual file schema and normalize to validated strings
explicitly; never assume a uniform id dtype across CCD files. See variable-definitions.md for the
per-file detail and the canonical materialization rules.
Missing Data Codes
The Portal uses both null and negative integer codes to represent missing/special values. The specific pattern varies by dataset:
| Code | Meaning | When Used |
|---|
null | Not available | Common in Directory fields that don't apply to all years |
-1 | Missing/not reported | Data not reported by state |
-2 | Not applicable | Item doesn't apply to this entity |
-3 | Suppressed | Data suppressed for privacy |
-9 | Not reported | State did not report this item |
Check actual data. Some datasets use null where others use -1 for effectively the same condition. Always check the observed values in the data before applying a blanket missing-value filter.
School Types (school_type)
| Code | Type | Description |
|---|
| 1 | Regular | Standard public school |
| 2 | Special Education | Focuses on students with disabilities |
| 3 | Vocational | Career/technical education focus |
| 4 | Alternative | Non-traditional programs |
| 5 | Reportable Program | Program within another school (2007-08+) |
LEA Types (agency_type)
| Code | Type | Description |
|---|
| 1 | Regular | Locally governed school district |
| 2 | Component | District sharing superintendent with others |
| 3 | Supervisory Union | Admin services for multiple districts |
| 4 | Regional Agency | Education service agency |
| 5 | State-operated | State-run schools (deaf, blind, correctional) |
| 6 | Federal-operated | Federal schools (BIE, DoDEA) |
| 7 | Charter Agency | All schools are charters (2007-08+) |
| 8 | Other | Doesn't fit other categories (2007-08+) |
| 9 | Specialized Agency | Specialized public agency (observed in data) |
Grade -1 Encoding
In CCD enrollment data:
grade = -1 means Pre-Kindergarten, NOT missing datagrade = 99 means Total across all grades
Do NOT filter grade >= 0 — this removes all Pre-K students!
df = df.filter(pl.col("grade") >= 0)
pre_k = df.filter(pl.col("grade") == -1)
k12 = df.filter(pl.col("grade").is_between(0, 12))
total = df.filter(pl.col("grade") == 99)
library(dplyr)
df <- df |> filter(grade >= 0)
pre_k <- df |> filter(grade == -1)
k12 <- df |> filter(grade >= 0, grade <= 12)
total <- df |> filter(grade == 99)
Portal Column Name Mapping
Variable Name Mapping: The Portal column urban_centric_locale contains locale codes. Some documentation may refer to this as simply locale. Use urban_centric_locale when filtering or selecting columns in Portal data.
Dataset-to-Component Mapping
| Mirror Dataset | CCD Component | Path |
|---|
| Schools CCD Directory | School Directory | ccd/schools_ccd_directory |
| Schools CCD Enrollment | School Membership | ccd/schools_ccd_enrollment_{year} |
| Districts LEA Directory | LEA Directory | ccd/school-districts_lea_directory |
| Districts CCD Enrollment | LEA Membership | ccd/schools_ccd_lea_enrollment_{year} |
| Districts CCD Finance | F-33 District Finance | ccd/districts_ccd_finance |
Data Collection Flow
Schools → Local Education Agencies (LEAs)
↓
State Education Agencies (SEAs)
↓
EDFacts Submission System
↓
NCES Quality Review & Editing
↓
CCD Public Data Files
Timeline: Data for school year 20XX-YY typically submitted spring 20YY, released fall 20YY (preliminary) to spring 20YY+1 (provisional/final).
Data Access
Data for the 2023-24 school year (file year 2024) is available. The current versioned mirror (Portal v0.26.1, v2 build validated 2026-08-06) carries CCD content spanning 1986-2024: directory and enrollment reach file year 2024, while district finance remains at 2020. See datasets-reference.md for canonical paths, mirrors.yaml for mirror configuration, and fetch-patterns.md for fetch code patterns.
Key datasets (5 dataset families; see datasets-reference.md for the authoritative list):
| Dataset | Type / coverage (v2 mirror, 2026-08-06) | Path | Codebook |
|---|
| School Directory | Single, through 2024 | ccd/schools_ccd_directory | ccd/codebook_schools_ccd_directory |
| School Enrollment | Yearly, 1986-2024 | ccd/schools_ccd_enrollment_{year} | ccd/codebook_schools_ccd_enrollment |
| District Directory | Single, through 2024 | ccd/school-districts_lea_directory | ccd/codebook_districts_ccd_directory |
| District Enrollment | Yearly, 1986-2024 | ccd/schools_ccd_lea_enrollment_{year} | ccd/codebook_districts_ccd_enrollment |
| District Finance | Single, through 2020 | ccd/districts_ccd_finance | ccd/codebook_districts_ccd_finance |
Verification sources: The 1986-2024 span (finance at 2020) is confirmed by the v2 mirror build validation (content-based year table, 2026-08-06). The underlying declaration sources — Portal endpoint catalog, Portal bulk manifest, and NCES CCD files — were last consulted 2026-07-27. Catalog years and labels are declarations; verify actual rows/files for the selected surface.
Not in Portal mirrors: The following CCD components are documented in this skill for reference but are not available through the Education Data Portal mirrors:
- Dropout/Completers — completion and dropout data by demographics
- State Finance (NPEFS) — state-level education revenue and expenditure
For these components, access NCES directly at https://nces.ed.gov/ccd/.
Codebooks are .xls files co-located with data in all mirrors. Use get_codebook_url() from fetch-patterns.md to construct download URLs:
url = get_codebook_url("ccd/codebook_schools_ccd_directory")
mirrors <- yaml::read_yaml("mirrors.yaml")
url <- paste0(mirrors$mirrors[[1]]$root_url, "ccd/codebook_schools_ccd_directory.xls")
Truth Hierarchy: When interpreting variable values, apply this priority:
- Actual data file (what you observe in the parquet/CSV) -- this IS the truth
- Live codebook (.xls in mirror) -- authoritative documentation, may lag
- This skill documentation -- convenient summary, may drift from codebook
If this documentation contradicts the codebook, trust the codebook. If the codebook contradicts observed data, trust the data and investigate.
Filtering
All filtering is done locally with Polars after download:
import polars as pl
df = df.filter(pl.col("fips") == 6)
df = df.filter(pl.col("year").is_in([2020, 2021, 2022]))
df = df.filter(pl.col("grade") == 99)
df = df.filter(pl.col("grade").is_between(0, 12))
library(dplyr)
df <- df |> filter(fips == 6)
df <- df |> filter(year %in% c(2020, 2021, 2022))
df <- df |> filter(grade == 99)
df <- df |> filter(grade >= 0, grade <= 12)
Finance Data Notes
- Finance coverage: District finance (
districts_ccd_finance) reaches 2020 in the v2 mirror (build validated 2026-08-06; the file was byte-stable content between the v0.24.0 and v0.26.1 vintages). Treat that as a dated Portal-surface cutoff, not a timeless statement about current NCES files.
- Finance dataset has 163 columns -- by far the most complex CCD dataset
- Some finance columns use
_total suffix (e.g., exp_current_instruction_total)
leaid is String type in Finance data (unlike the Districts Directory where it is Int64)
API vs. Bulk Representation
teachers_fte precision differs by delivery channel (verified 2026-08-07): the live Portal API serves teachers_fte (school directory) integer-rounded, while bulk-file-derived data (and the mirror) carries 2-decimal precision — cell-exact against the bulk CSV (e.g., 28.98 in the CSV and mirror vs. 28.0 returned by the API). API and bulk representations can differ even at the same Portal version, so prefer the bulk/mirror value when precision matters and note the source channel when reporting.
Common Pitfalls
| Pitfall | Issue | Solution |
|---|
| Summing grades | Misses ungraded students | Use grade=99 (total) instead |
Assuming -1 is missing | In enrollment grade data, -1 = Pre-K | Check variable format in codebook |
Reading highest_grade_offered == -1 as a grade | In directory grade-span (GSLO/GSHI), -1 = MISSING, not Pre-K/≥9 | Exclude -1 before grade-span filters (see variable-definitions.md) |
| Cross-state comparison | Different state definitions | Check state methodology first |
| Using FRPL as poverty measure | CEP schools show 100% | Supplement with MEPS or SAIPE data |
| Locale time series | 2006 code system change | Analyze pre/post-2006 separately |
| Charter school counts | Early years incomplete | Verify against state records pre-2010 |
| Dropout rate comparison | State definitions vary | Within-state comparisons only |
| Using NCES string codes | Portal uses integers | See variable-definitions.md for mappings |
Assuming charter=1/2 | Portal uses 0=No, 1=Yes | Empirically verified; not NCES 1=Yes, 2=No |
| Identifier type/width across files | Prior HF Parquet objects may expose integer leaid/ncessch, losing leading-zero/display-width semantics | Normalize to strings; validate leaid length 7 and ncessch length 12 before joining |
Coverage Notes
What CCD Includes
- All public schools (traditional, charter, magnet, alternative)
- All public school districts and LEAs
- Bureau of Indian Education (BIE) schools
- Department of Defense Education Activity (DoDEA) schools
- State-operated schools (deaf, blind, correctional)
What CCD Excludes
- Private schools (use Private School Universe Survey - PSS)
- Homeschool students
- Postsecondary institutions (use IPEDS)
- Detailed student-level data (CCD is aggregate only)
Related Data Sources
| Source | Relationship | When to Use |
|---|
education-data-source-edfacts | CCD nonfiscal data flows through EDFacts | Same underlying data |
education-data-source-crdc | Biennial; uses CCD school IDs | Need discipline, course access, equity data |
education-data-source-saipe | Uses CCD district IDs | Need poverty estimates (better than FRPL) |
education-data-source-meps | School-level poverty estimates | Need school-level poverty (better than FRPL) |
education-data-source-ipeds | Separate system for postsecondary | Need college/university data |
| PSS | Private school equivalent | Need private school data |
education-data-source-nhgis | Census geography crosswalks | Need school-Census links |
education-data-explorer | Parent discovery skill | Finding available datasets |
education-data-query | Data fetching (mirror system) | Downloading parquet/CSV files via fetch_from_mirrors() |
Topic Index
| Topic | Reference File |
|---|
| Directory survey | ./references/survey-components.md |
| Membership survey | ./references/survey-components.md |
| Staffing survey | ./references/survey-components.md |
| Finance surveys | ./references/survey-components.md |
| Dropout/completers | ./references/survey-components.md |
| Data collection process | ./references/data-collection.md |
| EDFacts submission | ./references/data-collection.md |
| Respondent universe | ./references/data-collection.md |
| NCES identifiers | ./references/variable-definitions.md |
| Missing data codes | ./references/variable-definitions.md |
| Grade codes | ./references/variable-definitions.md |
| Race/ethnicity codes | ./references/variable-definitions.md |
| Locale codes | ./references/variable-definitions.md |
| State-level variations | ./references/data-quality.md |
| Missing data patterns | ./references/data-quality.md |
| FRPL limitations | ./references/data-quality.md |
| Data suppression | ./references/data-quality.md |
| Locale code changes (2006) | ./references/historical-changes.md |
| Race/ethnicity changes (2010) | ./references/historical-changes.md |
| LEA type changes (2007) | ./references/historical-changes.md |
| ID changes over time | ./references/historical-changes.md |
