The new CA-08 crossed five counties, and one number had to be right.

The controlling question

The adopted boundary controls every number

District demographics look like a lookup until the lines move. The adopted CA-08 crossed Contra Costa, Sacramento, San Joaquin, Solano, and Yolo counties, and only Solano was wholly contained. Several cities that seemed geographically or historically associated with the district were not in it; others were split, so using a whole-city total would overstate the population the office actually represents. The governing rule Plavidian set at the start: the adopted district boundary, not a ZIP code, county line, prior configuration, or assumed city list, controls every calculation.

That rule corrected real assumptions. Vacaville was verified as wholly within the district. Davis and Lodi were verified as split, contributing only their district-contained portions. Antioch, Martinez, and Pittsburg, plausible inclusions on a casual map read, were verified as outside the district entirely.

The reconciliation

Five sources, one control total

No single dataset answers a redistricting question. The official district shapefile defined the legal boundary; Census TIGER/Line and 2020 block geography supplied the population units; Public Law 94-171 redistricting data carried population and race; Statewide Database city-split reports settled municipal containment; and the official district profile supplied the control totals everything had to reconcile against. Plavidian treated district geography as primary and municipal geography as a reporting layer, which is what keeps a split city from being double-counted or a county remainder area from vanishing.

The reconciliation surfaced a two-person difference between the published jurisdiction line items (760,064) and the official district total (760,066). Plavidian disclosed it instead of silently adjusting a component to force agreement: a documented source-table discrepancy is defensible, and an unsupported edit to an official figure is not.

What the numbers are for

Three populations, three different questions

The profile reports total population, voting-age population, and citizen voting-age population separately because they answer different questions: total population drives constituent services, infrastructure, and housing work; voting-age population counts all adults; citizen voting-age population matters for representation and language-access review. Reporting all three, with race and ethnicity at each level where the sources support it, keeps the office from applying one measure to a purpose it was never designed for. A separate methodology memorandum documents the sources, allocation rules, validation steps, and limitations, and states plainly what the report is not: voter registration, turnout, or campaign targeting.

The deliverable

A five-page memo built to be checked

The deliverable is a five-page memorandum, dense by design. The jurisdiction table above lists all 37 district-contained places (incorporated cities, unincorporated communities, and county remainder areas), each with its population and containment percentage, so a staffer can see at a glance that Crockett is 38.14% in the district while El Cerrito is wholly contained. Race and ethnicity are reported at three population levels: total, voting age, and citizen voting age. Every figure names its source (Senate Office of Demographics, the Statewide Database city-splits report, Census PL 94-171), and the memo closes with the full methodology, limitations, and a plain statement of what the report is not for. Nothing in it asks to be taken on faith.

Download the verified CA-08 memo (PDF)

Why it generalizes

The same method works for any custom boundary

The method applies wherever an office or agency needs a defensible profile of a geography that no published table matches: legislative and council districts, school and utility districts, service territories, grant zones, emergency-planning regions. Begin with the controlling legal boundary, integrate the smallest reliable population geography, verify every jurisdiction intersection, and reconcile the result to an authoritative control total. Accurate district demographics depend on verifying that every number belongs to the correct boundary.