How we know,and what we read.

This is the running record behind the map: the millage math, the official Pennsylvania files, and — as we collect them — the essays, posts, and reporting that make the case for supercomputers in ordinary towns. Campuses in the pipeline live on Proposed Campuses. Electric-rate stories live on Tax & Ratepayer Savings.

Methods

Pennsylvania real-estate tax is three millages stacked: county, municipality, and school district. A mill is $1 of tax per $1,000 of assessed value. We look up the house, read those three rates, then ask what happens if a supercomputer’s taxable real estate joins the same tax base and local governments keep collecting the same dollars.

new mills = current mills × tax base / (tax base + supercomputer assessed)
savings = home assessed × (current mills − new mills) / 1000

Where it sits matters. County millage can fall if the building is anywhere in Lancaster County. Municipal millage only if it is in that house’s borough or township. School millage only if it is in that house’s school district.
Land and buildings, not GPUs. Pennsylvania does not tax computers as real estate. Size on the map is an assumed taxable real-estate amount ($10 million per megawatt) — see Crémieux.
Homestead is school-tax only. If the parcel is homestead-approved, the exclusion comes off the school taxable value. Preferential / Clean & Green uses the preferential total when it is greater than zero.
This is an estimate. It is built from published millage and assessed value, not a tax collector’s invoice. Headline “investment” numbers usually mix buildings with computers Pennsylvania does not tax. County assessors will set the real number, and assessment ratios differ by county. The Proposed Campuses page uses the same $10 million per megawatt.

Pennsylvania sources

Millage is statewide. Parcel lookup is still Lancaster County. We re-download these when DCED or the county publishes a new year. We do not scrape MunStats HTML.

Pennsylvania Department of Community and Economic Development

Municipal and school real-estate tax rates

Reporting year 2026

Municipal mills and school-district mills for every Pennsylvania municipality × school district pair (2,625 real-estate totals, all 67 counties).

We use rows where Tax Name is “REAL ESTATE - TOTAL (mills).” That total is municipality + school only — it does not include county millage. Other levies (EIT, LST, realty transfer, hydrants) are out of scope. Tax-collector names and contact fields are stripped at ingest and never stored in the app.

Pennsylvania Department of Community and Economic Development

County tax rates

Reporting year 2026

A statewide county millage table. Lancaster’s DCED row still lists 2.911 mills (the 2025 adopted rate).

We do not use the DCED county figure for the bill. See the Lancaster County millage PDF below.

Lancaster County, Pennsylvania

2026 County–Municipal and 2025–2026 School millage

2026

County millage of 3.201 mills — the number on the county line of every bill in this app.

This conflicts with DCED’s still-published 2.911. We side with the county’s own 2026 schedule for the county line, and with DCED for municipal and school mills.

State Tax Equalization Board / Pennsylvania DCED library

2025 Market Value Report (revised 7/15/2026)

2025 tax year, revised July 15, 2026

Assessed-value tax bases: county (~$44.98B), each municipality, and each school district (Lancaster Tax County slice).

Millage applies to assessed value, not STEB market value. Grain is school district × municipality. Cross-county districts (Octorara, a sliver of Conrad Weiser) currently include only the Lancaster slice.

Lancaster County via DevNet

Lancaster County assessment / parcel pages (DevNet wEdge)

Tax year 2026 records

Household assessed value, homestead / Clean & Green flags, and a public link back to the official parcel page.

There is no public JSON API. We never POST the search form. PASDA supplies the account number; we GET the parcel page and reconstruct the bill from assessment × mills. Billing tab dollars are often blank. Owner names are not shown. Example: parcel 4407666400000 (129 E Charlotte St, Millersville).

PASDA / Lancaster County GIS

Lancaster County parcels (MapServer layer 21)

2026 parcels

Point-in-polygon parcel match. ACCOUNT is the same id DevNet uses (no dashes).

This layer does not carry assessed value. First three digits of ACCOUNT are the township code (440 = Millersville Borough).

PASDA / Lancaster County GIS

Lancaster County municipal boundaries (MapServer layer 8)

Current GIS extract

Which borough or township a house or supercomputer sits in — that picks municipal mills and the municipal tax base.

PASDA / Lancaster County GIS

Lancaster County school district boundaries (MapServer layer 15)

Current GIS extract

Which school district a point falls in — that picks school mills and whether a placement cuts school millage for that house.

District names on the layer are sometimes truncated (e.g. “Eastern Lancaster Count”). We match them to the DCED names in our millage table.

Reading

Articles, posts, and other writing that back the map. Titles open the original.

Crémieux on X

How large a data center would your town need to replace your property taxes?

August 20, 2026

The $10 million-per-megawatt figure on the map. Hyperscale building and infrastructure runs about $10–12 million per MW; if that construction is taxable, a 160–200 MW campus is roughly $2 billion of tax base.

Pennsylvania taxes land and buildings, not computers, so we use the low end. The post is a national sketch, not a Lancaster assessment.