Cgpt Census API

CGPT Census API

Use this skill for U.S. Census Bureau data workflows: finding variables, choosing geographies, building API URLs, writing R/Python fetch code, or explaining Census results.

Security And Currency

• Do not embed API keys in skill files, reports, scripts, or examples.
• Prefer CENSUS_API_KEY from the environment when a key is needed.
• If no key is available, use endpoints that work without a key for small queries or ask the user whether to provide one.
• Census datasets and vintages change. Verify available dataset years and variable names from Census metadata before relying on them for current work.
• If network access is required and unavailable, produce reproducible code and state that live verification was not run.

Workflow

1. Clarify the question:
   • geography: nation, state, county, tract, place, metro, ZCTA
   • dataset: ACS 1-year, ACS 5-year, ACS profile/subject, decennial, PEP, CBP, Economic Census
   • vintage/year
   • variables or table IDs
   • output format: table, CSV, R, Python, URL, map-ready data
2. Verify dataset and variable availability when live access is possible.
3. Build the query using get=, for=, and in= predicates.
4. Include NAME and relevant margin-of-error variables for ACS estimates when appropriate.
5. Return tidy output code and caveats about geography, vintage, margins of error, and suppressed/missing values.

Common Patterns

API shape:

https://api.census.gov/data/{year}/{dataset}?get=NAME,{variables}&for={geography}&in={container}

Washington examples:

• state FIPS: 53
• King County: 033
• Pierce County: 053
• Snohomish County: 061

ACS variable suffixes:

• E: estimate
• M: margin of error
• EA or MA: annotation

R Pattern

library(httr2)
library(jsonlite)

key <- Sys.getenv("CENSUS_API_KEY")
base <- "https://api.census.gov/data/2023/acs/acs5"
query <- list(
  get = "NAME,B19013_001E,B19013_001M",
  `for` = "county:*",
  `in` = "state:53"
)
if (nzchar(key)) query$key <- key

resp <- request(base) |> req_url_query(!!!query) |> req_perform()
raw <- resp_body_json(resp, simplifyVector = TRUE)

Python Pattern

import os
import requests

params = {
    "get": "NAME,B19013_001E,B19013_001M",
    "for": "county:*",
    "in": "state:53",
}
key = os.getenv("CENSUS_API_KEY")
if key:
    params["key"] = key

response = requests.get("https://api.census.gov/data/2023/acs/acs5", params=params, timeout=30)
response.raise_for_status()
rows = response.json()

Report Requirements

Always report:

• dataset and vintage
• geography and FIPS assumptions
• variables used and plain-English definitions
• whether live API verification ran
• limitations such as ACS margins of error, 1-year population thresholds, missing data, or vintage mismatch