# BLS Data Reference

Bureau of Labor Statistics — API access, dataset catalog, series ID formats, and field schemas.

## Quick Start

1. Register for an API key: https://data.bls.gov/registrationEngine/
2. Base API endpoint: `https://api.bls.gov/publicAPI/v2/timeseries/data/`
3. Content-Type: `application/json` (POST)

---

## API Versions

| Feature                   | v1 (no key) | v2 (registered) |
|---------------------------|-------------|-----------------|
| Daily query limit         | 25          | 500             |
| Series per query          | 25          | 50              |
| Years of history          | 10          | 20              |
| Net/percent changes       | No          | Yes             |
| Series descriptions       | No          | Yes             |
| Calculations              | No          | Yes             |

---

## Registration

- URL: https://data.bls.gov/registrationEngine/
- Free, no approval needed — instant key via email
- Key goes in the JSON payload as `"registrationkey": "YOUR_KEY"`

---

## Endpoints

### GET: Survey List
```
GET https://api.bls.gov/publicAPI/v2/surveys
GET https://api.bls.gov/publicAPI/v2/surveys/{survey_abbreviation}
```
Returns all survey codes and names. See `surveys.json` for full list.

### GET: Popular Series
```
GET https://api.bls.gov/publicAPI/v2/timeseries/popular
GET https://api.bls.gov/publicAPI/v2/timeseries/popular?survey={abbreviation}
```
Returns the 25 most-requested series IDs for a survey.

### POST: Time Series Data
```
POST https://api.bls.gov/publicAPI/v2/timeseries/data/
Content-Type: application/json
```

**Minimal request (unregistered):**
```json
{
  "seriesid": ["LAUST110000000000003", "CES0000000001"],
  "startyear": "2023",
  "endyear": "2025"
}
```

**Full request (registered, v2 features):**
```json
{
  "seriesid": ["LAUST110000000000003", "CES0000000001"],
  "startyear": "2020",
  "endyear": "2025",
  "registrationkey": "YOUR_KEY",
  "catalog": true,
  "calculations": true,
  "annualaverage": true,
  "aspects": true
}
```

**Response schema:**
```json
{
  "status": "REQUEST_SUCCEEDED",
  "responseTime": 114,
  "message": [],
  "Results": {
    "series": [
      {
        "seriesID": "LAUST110000000000003",
        "catalog": {
          "series_title": "...",
          "survey_name": "...",
          "measure_data_type": "..."
        },
        "data": [
          {
            "year": "2025",
            "period": "M12",
            "periodName": "December",
            "value": "6.4",
            "footnotes": [
              { "code": "R", "text": "Data were subject to revision on April 8, 2026." }
            ],
            "calculations": {
              "net_changes": { "1": "0.1", "3": "-0.2", "6": "0.5", "12": "-0.3" },
              "pct_changes": { "1": "1.6", "3": "-3.0", "6": "8.3", "12": "-4.5" }
            }
          }
        ]
      }
    ]
  }
}
```

**Period codes:**
- Monthly: `M01`–`M12`, `M13` (annual average)
- Quarterly: `Q01`–`Q04`, `Q05` (annual average)
- Annual: `A01`

**Status codes:** `REQUEST_SUCCEEDED`, `REQUEST_FAILED`, `REQUEST_NOT_PROCESSED`

**Error footnote codes:**
- `R` — Revised
- `P` — Preliminary
- `X` — Data unavailable (e.g., government shutdown gap)
- `N` — Not available

---

## Python Example

```python
import requests

API_KEY = "YOUR_KEY"
BASE_URL = "https://api.bls.gov/publicAPI/v2/timeseries/data/"

def get_series(series_ids, start_year, end_year):
    payload = {
        "seriesid": series_ids,
        "startyear": str(start_year),
        "endyear": str(end_year),
        "registrationkey": API_KEY,
        "catalog": True,
        "calculations": True,
        "annualaverage": True,
    }
    r = requests.post(BASE_URL, json=payload)
    r.raise_for_status()
    data = r.json()
    if data["status"] != "REQUEST_SUCCEEDED":
        raise ValueError(f"BLS API error: {data['message']}")
    return data["Results"]["series"]

# DC unemployment rate (LAUS)
series = get_series(["LAUST110000000000003"], 2020, 2025)
for obs in series[0]["data"]:
    print(obs["year"], obs["periodName"], obs["value"])
```

---

## Bulk Download (flat files)

Base URL: `https://download.bls.gov/pub/time.series/`

Each survey folder contains:
- `{prefix}.series` — master list of all series IDs with metadata
- `{prefix}.data.{N}.{name}` — actual observations, split by category
- `{prefix}.{dimension}` — lookup/decode tables (area, industry, measure, etc.)

Key folder prefixes:
```
la/   — LAUS (local area unemployment)
ce/   — CES national employment
sm/   — State & Metro employment (CES state)
en/   — QCEW
oe/   — OES (occupational employment)
jt/   — JOLTS
cu/   — CPI-U
wp/   — PPI commodities
```

Files are tab-delimited. Useful for bulk PostgreSQL ingest.

---

## Files in this folder

- `README.md` — this file
- `surveys.json` — complete survey list from the API
- `series_id_formats.md` — series ID decode tables for each key dataset
- `qcew_field_schema.md` — QCEW quarterly and annual CSV field layouts
- `api_response_example.json` — real API response sample