US Census Bureau

Population Clock API

JSON-feed driving the U.S. and world Population Clock — current population estimates plus estimated time intervals for births, deaths, and net international migration. Public, no key required.

Population Clock API is one of 7 APIs that US Census Bureau publishes on the APIs.io network, described by a machine-readable OpenAPI specification.

This API exposes 1 machine-runnable capability that can be deployed as REST, MCP, or Agent Skill surfaces via Naftiko.

Tagged areas include Government, Demographics, and Real Time. The published artifact set on APIs.io includes an OpenAPI specification and 1 Naftiko capability spec.

Documentation GitHub OpenAPI

Specifications

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OpenAPI

https://raw.githubusercontent.com/api-evangelist/us-census-bureau/refs/heads/main/openapi/census-population-clock-api-openapi.yml

Other Resources

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Portal

https://www.census.gov/popclock/

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NaftikoCapability

https://raw.githubusercontent.com/api-evangelist/us-census-bureau/refs/heads/main/capabilities/census-population-clock-clock.yaml

OpenAPI Specification

openapi: 3.1.0
info:
  title: Population Clock API
  description: |
    JSON feeds that drive the U.S. and World Population Clock. The U.S. clock
    publishes the current resident population estimate and the interval (in
    seconds) between births, deaths, and net international migration events.
    The world clock publishes the current world population estimate.

    No API key required.
  version: '2026-05-25'
  contact:
    name: Census Bureau Population Division
    url: https://www.census.gov/popclock/
  license:
    name: Public Domain
    url: https://www.usa.gov/government-works
servers:
- url: https://www.census.gov
  description: census.gov public web
paths:
  /popclock/data/population/uspop.json:
    get:
      summary: Get U.S. Population Clock Snapshot
      description: Current U.S. resident population estimate and event intervals (birth, death, net migration).
      operationId: getUsPopClock
      responses:
        '200':
          description: U.S. population clock snapshot
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/UsPopClock'
  /popclock/data/population/world.json:
    get:
      summary: Get World Population Clock Snapshot
      description: Current world population estimate.
      operationId: getWorldPopClock
      responses:
        '200':
          description: World population snapshot
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/WorldPopClock'
components:
  schemas:
    UsPopClock:
      type: object
      properties:
        population:
          type: integer
          description: Current U.S. resident population estimate.
        births:
          type: number
          description: Seconds between births.
        deaths:
          type: number
          description: Seconds between deaths.
        netInternationalMigration:
          type: number
          description: Seconds between net international migration events.
        populationChange:
          type: number
          description: Seconds between net population changes.
        reference:
          type: string
          format: date-time
    WorldPopClock:
      type: object
      properties:
        population:
          type: integer
        reference:
          type: string
          format: date-time