census.demographics

US Census ACS 5-year demographics for a state or county. Give a state (2-letter or 2-digit FIPS), optionally a 3-digit county FIPS, and get population, median age, median household income, per-capita income, poverty rate (computed), households, owner-occupancy rate (computed), median home value, and median gross rent. Free, public-domain (US Census Bureau). Complements census.zipcode (ZIP/ZCTA-level) with state- and county-level geography. Authoritative demographic data an LLM cannot recall — for market sizing, site selection, and socioeconomic research.

price

$0.0011 USDC per call

method

GET/api/census/demographics

payment

x402 v2 · USDC on Base (EIP-3009) or Solana (SPL transfer)

auth

None. Sign the payment, retry with PAYMENT-SIGNATURE.

tier

Tier 0 — no paid upstream

Parameters

Name	Type	Description
`state`required	string	2-letter state code or 2-digit FIPS. min 2 chars · max 2 chars
`county`	string	match ^\d{3}$
`year`	integer	min 2010 · max 2100

Code samples

cURLbash

# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/census/demographics?state=xx&county=12345&year=2010'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/census/demographics?state=xx&county=12345&year=2010' \
  -H 'PAYMENT-SIGNATURE: <base64-json-payload>'

# Or use the canonical runner (handles probe → sign → retry):
#   EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
#     --experimental-strip-types scripts/x402-pay.ts \
#     'https://2s.io/api/census/demographics?state=xx&county=12345&year=2010'

TypeScript / Node — @2sio/sdktypescript

import { TwoS } from '@2sio/sdk'

const client = new TwoS({
  privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})

const result = await client.census.demographics({
  "state": "xx",
  "county": "12345",
  "year": 2010
})

console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)

Python — 2siopython

import os
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

result = client.census.demographics(state="xx", county="12345", year=2010)

print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)

MCP — Claude Desktop / AgentKit / any MCP hostjson

// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
//    EVM_PRIVATE_KEY funds x402 payments per call.

// claude_desktop_config.json
{
  "mcpServers": {
    "2sio": {
      "command": "npx",
      "args": ["-y", "@2sio/mcp"],
      "env": { "EVM_PRIVATE_KEY": "0x..." }
    }
  }
}

// 2. Once the server is running, agents call this tool via standard MCP:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "census.demographics",
    "arguments": {
      "state": "xx",
      "county": "12345",
      "year": 2010
    }
  }
}

Response

Field	Type	Description
`ok`	boolean	one of: true
`items`	array
`total`	integer	Total matching rows upstream; null when unknown.
`source`	object

Example response datajson

{
  "ok": true,
  "items": [
    {
      "query": {
        "state": "example",
        "county": "example",
        "year": 1
      },
      "geoName": "example",
      "population": 1,
      "medianAge": 1,
      "medianHouseholdIncomeUSD": 1,
      "perCapitaIncomeUSD": 1,
      "povertyRate": 1,
      "households": 1,
      "ownerOccupancyRate": 1,
      "medianHomeValueUSD": 1,
      "medianGrossRentUSD": 1,
      "source": {
        "provider": "example",
        "url": "example",
        "license": "example"
      },
      "note": "example"
    }
  ],
  "total": 1,
  "source": {
    "provider": "example",
    "url": "example",
    "license": "example"
  }
}

Discovery

/api/directory — full catalog of every endpoint
/openapi.json — OpenAPI 3.1 spec (per-op x-payment-info, x402Payment security)
/.well-known/x402 — machine-readable service descriptor for x402-aware crawlers
/.well-known/mcp/server-card.json — MCP SEP-1649 server card
/llms.txt — plain-text manifest for LLM ingestion

2s.io is x402-native. Every call is paid per-request from a USDC-funded EVM wallet on Base — no signup, no API keys, no monthly fees. Source code: github.com/2s-io/sdk.