Peninsula School Enrollment vs. Housing Production

Rebuts the "new housing overwhelms schools" argument by showing that K-12 enrollment in most San Mateo County districts has been falling for a decade — and new housing construction has not reversed that.

Live: https://yourusername.github.io/enrollment-vs-housing

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What this shows

Claim	What the data shows
"More housing = more kids in schools"	Enrollment peaked in most SMC districts around 2015–2017 and has declined since
"We can't build until schools are ready"	The districts building the most units have seen no enrollment reversal
"Our schools are already full"	Most elementary districts have lost 5–15% of students since their peak

Data sources

Source	What	Years	URL
CA Dept. of Education Census Day Enrollment	K-12 enrollment by district	2014–15 → 2023–24	cde.ca.gov
HCD Housing Element APR	Building permits by jurisdiction + income category	2018 → 2023	data.ca.gov
Census Bureau BPS	Annual permit totals (pre-APR supplement)	2010–2017	census.gov

Quickstart

git clone https://github.com/yourusername/enrollment-vs-housing
cd enrollment-vs-housing
make install
make run

This downloads ~30 MB of raw data, processes it, and writes docs/data/viz_data.json. Open docs/index.html in a browser to see the visualization.

Pipeline

pipeline/
  config.py            # All URLs, constants, jurisdiction→district crosswalk
  fetch_enrollment.py  # CDE enrollment (two file format eras)
  fetch_housing.py     # HCD APR + Census BPS
  merge.py             # Join + compute indices → viz_data.json
  run_all.py           # Orchestrator

Raw files are cached in data/raw/ (gitignored). The final JSON (docs/data/viz_data.json) is committed and served by GitHub Pages.

Known data quality issues

1. TK discontinuity (2022–23 → 2023–24): CDE changed how TK is reported. The pipeline uses K-12 only for consistency; see config.py for the TK supplement option.

2. APR self-reporting noise: HCD APR data is self-reported by jurisdictions. Duplicate entries and misassigned years occur. The pipeline deduplicates by keeping the latest submission per jurisdiction+year. See Possibility Lab (2024) for a full accounting.

3. Jurisdiction ↔ district crosswalk: This is manually curated. Redwood City feeds two elementary districts; some cities straddle district lines. Review JURISDICTION_DISTRICT_MAP in config.py and correct as needed.

4. HCD APR URL: The CSV resource URL on data.ca.gov has changed once since 2022. If fetch_housing.py fails, the CKAN API fallback will auto-discover the current URL; failing that, update HCD_APR_CSV_URL in config.py.

Deployment (GitHub Pages)

1. In repo Settings → Pages, set source to docs/ folder on main.
2. The refresh_data.yml workflow runs weekly and commits an updated viz_data.json.
3. The React app is a single static docs/index.html — no build step needed.

License

Data: California Open Data (CC BY) and Census Bureau (public domain).
Code: MIT.