Data & Corrections
Where our data comes from, how current it is, what a rating does and doesn’t tell you, known limitations, how to report an error, and a dated log of corrections we’ve made. This page is a plain factual account, not a marketing pitch — see Methodology and How Ratings Work for the full calculation walkthrough.
Where the data comes from
Every number on this site traces back to one of four public sources. Nothing is estimated by us beyond the specific per-pupil-spending modeling disclosed on the Methodology page.
| What it covers | Source |
|---|---|
| District names, LEAIDs, enrollment, school counts, contact info | NCES Common Core of Data (CCD) |
| Ratings for districts in 24 states (see list below) | Each state's own current assessment program |
| Ratings for districts in the remaining states | U.S. Dept. of Education EDFacts collection |
| ZIP-to-district assignment | US Census TIGER/Line district boundaries + Census ZCTA centroids |
| District boundary maps | US Census TIGER Web Services (live) |
The 24 states with their own assessment overlay: AZ, CA, CO, FL, GA, IA, IL, IN, KY, MA, MD, MN, MO, NC, NJ, NY, OH, PA, TN, TX, UT, VA, WA and WI. Every zip page states the exact source and school year behind its own rating. The full dataset, including per-district state percentile and source year, is downloadable as CSV on the Open Data page under CC BY 4.0.
How current the data is, source by source
We would rather state a source's age honestly than imply everything is equally fresh. It isn't:
- Federal EDFacts ratings (states without their own overlay): school year 2021–22, the most recent federal district-level file available, with a 2017–18 fallback where a district has no record in the newer file. Nationwide standardized testing was paused in 2020, which is part of why this collection is older than the directory data below.
- State-overlay ratings (24 states): each state's own most recently published assessment cycle — for example Massachusetts MCAS 2024–25, Texas STAAR 2023, Tennessee TCAP 2025–26, Colorado CMAS 2025. These are newer than the federal collection because they come directly from the state rather than through the federal reporting pipeline.
- District directory data (names, enrollment, school counts, contacts): NCES Common Core of Data 2024–2025, refreshed annually when NCES releases a new CCD file.
- Per-pupil spending: NCES CCD Fiscal data for the highest-enrollment districts, most recently 2019–2020 (the latest year with real district-level CCD finance data); a modeled estimate not tied to a specific year for the remaining districts.
- District boundary maps: loaded live from Census TIGER Web Services on every page view — always current with what Census publishes.
What the rating does — and doesn’t — measure
A rating is the average of a district's reading and math proficiency rates — the share of students scoring proficient or above on state assessments — percentile-ranked against every other district in the same state, and converted to a 1–10 score.
It does not measure:
- Teacher quality, school safety, extracurriculars, or facilities
- Graduation rates or college outcomes
- Spending, staffing ratios, or administrative efficiency
- Any individual school — a district score is a district-wide average; specific schools may perform well above or below it
Because it is a within-state percentile, a rating is not comparable between states — a 7/10 in one state reflects a different underlying proficiency level than a 7/10 in another. Hawaii operates as a single statewide school district, so there is no in-state peer group to rank against; Hawaii pages show “Not comparable” rather than a number.
Known limitations
- ZIP-to-district mapping is approximate. ZIP code boundaries do not follow school district boundaries. We assign each ZIP to the district covering its Census ZCTA centroid point, which is usually but not always the district that actually serves a given address — fringe addresses can fall in a neighboring district.
- Charter and private schools are not included in district assignments; NCES CCD covers public school districts only.
- Intra-district school choice is not reflected. Some districts allow open enrollment across schools within the district.
- Some districts are shown as “Not rated.” This happens where the Department of Education does not publish district-level proficiency — typically very small districts whose scores are suppressed for privacy, or large systems (such as New York City) that report at the sub-district level. We show no rating rather than a guess.
- Ratings are relative, not absolute, and are one data point among many. Test scores reflect many factors beyond teaching, including local economic conditions.
- Always verify with your local district before making enrollment, housing, or school-choice decisions.
How to report an error
If something on this site looks wrong, email [email protected] with:
- The ZIP code or district page in question
- What you believe is wrong
- A link to the authoritative source you're comparing against (NCES, your state department of education, or your district's own site)
What happens next: we check the report against our source data and the authoritative source you provided. If it's a data error, we correct it and, for substantive corrections, add a dated entry to the changelog below. We aim to respond within 5 business days.
Changelog of data corrections
On 2026-08-10 and 2026-08-11 we ran a data-integrity audit across the site and corrected several classes of error. In the interest of transparency, here is what was wrong and what changed:
Some district pages stated a specific student-teacher ratio and a specific per-pupil spending figure as if measured for that district. Neither is a district-level measurement in our source data: the ratio was a constant per state (for example, every Alaska ZIP page showed the same 11:1 regardless of district), and the spending figure came from a state-level table. We reworded these sentences to attribute the figures to the state, which is what they actually are.
A page's FAQ text stating district enrollment and school counts had, on pages where neither NCES nor the page's own data held a real figure for that district, been filled in with generic round numbers (for example, "5,500 students across 10 schools") instead of being left blank. Those invented figures were removed rather than replaced with another guess.
On 6,001 district pages, the FAQ text stated an enrollment and school count that disagreed with the structured district-data block on the same page. We checked both figures against NCES: the structured data block was correct in 5,906 of those cases and the FAQ text was correct in none of them. The FAQ text was resynced to match the verified figures (or, where no source had a real figure, the sentence was dropped — see above).
Five ZIP codes (03215 Waterville Valley NH, 03593 Randolph NH, 54850 La Pointe WI, 85341 Lukeville AZ, and 55111 in Saint Paul MN) carried a federal placeholder code meaning “district not defined” and displayed the literal text “School District Not Defined”; each was researched individually and assigned to its real district. A sixth, 82930 (Evanston, Uinta County, Wyoming), had been assigned to a Utah district; it was reassigned to Uinta County School District 1, the Wyoming district that actually serves it. Separately, one more ZIP, 40032 (La Grange, Oldham County, Kentucky), had been assigned to an Indiana district about 100 miles away; it was corrected to Oldham County School District, the same district as its neighboring Kentucky ZIP codes.
On a set of pages generated by cloning a template from another ZIP, the “nearby ZIP codes are served by…” text still named the template's neighboring districts rather than the page's own. For example, a Lukeville, Arizona page (on the Mexican border) named two districts as its nearest neighbors that were actually roughly 200 miles north and in the Phoenix metro area. We recomputed real neighboring districts from each page's own coordinates against every other district's ZIP coverage.
The meta/description text on some pages named the wrong city in its locality parenthetical — on template-cloned pages, sometimes the template's originating city rather than the page's own. We corrected the locality to match each page's own district-data block.
Our Methodology and How Ratings Work pages previously stated that every rating was built entirely from the federal EDFacts collection. That was inaccurate for roughly half the site: districts in 24 states are rated from that state's own current assessment data instead, as individual ZIP pages already correctly disclosed. We corrected the two site-level pages to describe both sources and added an explicit note that ratings are not comparable between states.
Six district pages displayed the name of a different, real school district, and in five of those cases two separate pages showed the identical name. Greenwood Community School Corporation (IN) appeared as Clark-Pleasant; Hamilton Local (OH) as Teays Valley; Collingswood Borough (NJ) as Oaklyn; Clementon Borough (NJ) as Lindenwold; Shandon Joint Unified (CA) as Paso Robles Joint Unified; and Kim Reorganized 88 (CO) as Branson Reorganized 82. Ten zip codes were affected — 46143, 43137, 43217, 08107, 08021, 93451, 93461, 81027 and 81049 — where a reader would have been told they were in a neighboring district. The most serious was Shandon, a 271-student district shown as Paso Robles Joint Unified, which has 6,341 students. Separately, Miller Creek Elementary School District (CA) was still shown under the name it retired in 2019. All seven now use the name in the NCES Common Core of Data directory.
Each page states which assessment its rating comes from. On 186 pages in Pennsylvania, Utah, Ohio, Iowa and Kentucky that line still credited federal EDFacts data (2017–18 or 2021–22) for a rating that was actually computed from the state’s own current assessment — PSSA 2024–25, RISE/Aspire 2024–25, Ohio State Tests 2024–25, ISASP 2024–25 and KSA 2024–25 respectively. The ratings themselves were correct; the attribution was not. Pages whose district is genuinely rated from EDFacts, because no state overlay covers it, were left unchanged.
Each county page lists the districts in that county, built from our zip-to-district crosswalk. Districts serving no zip code in that crosswalk therefore never appeared — 1,564 of them nationally, including 484 with more than 1,000 students. Most are elementary or secondary districts that share territory with a partner district. They are now listed from the NCES directory, marked with 0 zip codes and explained beneath the table, so a county page shows the whole county.