`zip_code`: a 5-digit US ZIP. A good first call to validate a ZIP before
asking for more detail. Returns the ZCTA, Census area name, total population,
and the ACS data vintage. ZIP ≈ ZCTA; ~2% of ZIPs have no ZCTA and error.

`zip_code`: a 5-digit US ZIP. Returns median household income, per-capita
income, the number of households, and the percent of households earning
$200k+ — all ACS 5-year estimates in USD. Note: ACS top-codes median
household income at $250,001, so the wealthiest ZIPs (e.g. Atherton 94027)
report exactly that — read it as "$250k or more," not an exact figure.

`zip_code`: a 5-digit US ZIP. Returns the total population and the median
age of residents — both ACS 5-year estimates. (Age-bracket breakdowns,
e.g. under-18 / 18-34 / 35-64 / 65+, are on the roadmap.)

`zip_code`: a 5-digit US ZIP. Returns the median value of owner-occupied
homes, the median gross rent (monthly), the number of occupied housing
units, and the percent that are owner-occupied — all ACS 5-year estimates.
Note: ACS top-codes median home value at $2,000,001, so the priciest ZIPs
(e.g. Atherton 94027) report exactly that — read it as "$2M or more," not an
exact value.

`zip_code`: a 5-digit US ZIP. Of the population aged 25 and over, returns
the percent with a bachelor's degree or higher and the percent with a
graduate or professional degree — ACS 5-year estimates.

`zips`: a list of 5-digit US ZIPs to compare. `metric`: one of
`population`, `median_age`, `median_household_income`, `per_capita_income`,
`households_200k_plus_pct`, `median_home_value`, `median_gross_rent`,
`owner_occupied_pct`, `bachelors_plus_pct`, `graduate_or_professional_pct`.
Returns each ZIP's value, sorted descending; ZIPs with no data (suppressed
or no ZCTA) are listed last. All values are ACS 5-year estimates.

`zip_code`: a 5-digit US ZIP. `variable`: an ACS variable code (e.g.
`B19013_001E`) or the friendly store-column name (e.g.
`median_household_income`); both match case-insensitively. Returns that one
value for the ZIP. Limited to the variables held in the local store (the
same ones the other tools draw on); an unknown variable errors with the
full list.

`place`: a U.S. place name — an incorporated city/town or a census-designated
place (e.g. 'Cambridge', 'West Hollywood'); the Census descriptor is optional
('Cambridge' and 'Cambridge city' both work). `state`: optional 2-letter USPS
code or full state name to disambiguate (many places share a name). Returns
the ZCTAs intersecting that place, ranked by `coverage_pct` — the share of
each ZCTA's land that lies within the place. This is approximate: ZCTAs don't
nest inside places, so a ZIP may span several places and vice versa. Built on
the public 2020 Census ZCTA-to-Place relationship file (no API key needed).