Added authoritative U.S. GDP data from FRED/BEA covering 96 years of economic history: - Real GDP quarterly data: Q1 1947 - Q2 2025 (314 data points) - Real GDP annual data: 1929 - 2024 (96 data points) Includes comprehensive research-backed documentation: - Complete source verification (10 parallel research agents, 95%+ confidence) - Full methodology documentation and data quality standards - Download instructions, APIs, and update procedures - Historical context from Great Depression through COVID-19 Updated main README with Data directory documentation and dataset comparison table. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
259 lines
8.7 KiB
Markdown
259 lines
8.7 KiB
Markdown
# U.S. GDP Data Resources
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This document provides direct links to data sources, APIs, and tools for accessing U.S. GDP data.
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## Primary Data Sources
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### FRED (Federal Reserve Economic Data)
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**Official Website:**
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- Main Portal: https://fred.stlouisfed.org
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- About FRED: https://fred.stlouisfed.org/about
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**Real GDP Series Pages:**
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- **GDPC1** (Quarterly Real GDP): https://fred.stlouisfed.org/series/GDPC1
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- **GDPCA** (Annual Real GDP): https://fred.stlouisfed.org/series/GDPCA
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- **GDP** (Quarterly Nominal GDP): https://fred.stlouisfed.org/series/GDP
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**Direct CSV Downloads:**
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```bash
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# Quarterly Real GDP (GDPC1) - 1947 to present
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curl -L "https://fred.stlouisfed.org/graph/fredgraph.csv?id=GDPC1" -o gdpc1.csv
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# Annual Real GDP (GDPCA) - 1929 to present
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curl -L "https://fred.stlouisfed.org/graph/fredgraph.csv?id=GDPCA" -o gdpca.csv
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# Quarterly Nominal GDP (GDP) - 1947 to present
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curl -L "https://fred.stlouisfed.org/graph/fredgraph.csv?id=GDP" -o gdp.csv
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```
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**FRED API:**
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- API Documentation: https://fred.stlouisfed.org/docs/api/fred/
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- API Key Signup: https://fredaccount.stlouisfed.org/apikeys
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- Free tier available with rate limits
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- RESTful API with JSON/XML responses
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**FRED API Example:**
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```bash
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# Get Real GDP data via API (requires API key)
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curl "https://api.stlouisfed.org/fred/series/observations?series_id=GDPC1&api_key=YOUR_API_KEY&file_type=json"
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```
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### Bureau of Economic Analysis (BEA)
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**Official Website:**
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- BEA Homepage: https://www.bea.gov
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- GDP Data Portal: https://www.bea.gov/data/gdp/gross-domestic-product
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**Interactive Data Tools:**
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- Interactive NIPA Tables: https://apps.bea.gov/itable/
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- Navigate to: National → GDP & Personal Income → Section 1 (Domestic Product and Income)
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- Table 1.1.6: Real Gross Domestic Product, Chained Dollars
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- iTable Interface: https://apps.bea.gov/itable/?ReqID=70&step=1
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**BEA API:**
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- API Home: https://apps.bea.gov/api/signup/
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- API Documentation: https://apps.bea.gov/api/bea_web_service_api_user_guide.htm
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- API Key Signup: https://apps.bea.gov/api/signup/ (free, instant email delivery)
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- Supports JSON and XML output
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**BEA API Example:**
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```bash
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# Get GDP data via BEA API (requires free API key)
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curl "https://apps.bea.gov/api/data/?UserID=YOUR_API_KEY&method=GetData&datasetname=NIPA&TableName=T10106&Frequency=Q&Year=X&ResultFormat=json"
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```
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**Key NIPA Tables:**
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- Table 1.1.6: Real GDP (Quarterly and Annual)
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- Table 1.1.5: Nominal GDP (Quarterly and Annual)
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- Table 1.1.9: Implicit Price Deflators for GDP
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**News Releases:**
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- GDP News Release: https://www.bea.gov/news/blog/2024-09-26/gross-domestic-product-second-quarter-2024-third-estimate
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- Release Schedule: https://www.bea.gov/news/schedule
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## Extended Historical Data
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### MeasuringWorth (1790-Present)
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**Website:** https://www.measuringworth.com/datasets/usgdp/
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**Coverage:** U.S. GDP from 1790 to present (links historical estimates to modern BEA data)
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**Key Researchers:**
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- Louis Johnston (College of Saint Benedict / Saint John's University)
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- Samuel H. Williamson (University of Illinois at Chicago - emeritus)
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**Methodology:**
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- Pre-1929 data based on economic historians' research:
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- Weiss (1799-1829)
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- Gallman (1839-1909 benchmarks)
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- Kendrick (1909-1928)
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- Post-1929: Official BEA data
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**Download:** Available as CSV from MeasuringWorth website
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## Related Federal Reserve Resources
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### GDPNow (Real-Time GDP Forecasting)
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**Atlanta Fed GDPNow Model:**
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- Website: https://www.atlantafed.org/cqer/research/gdpnow
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- Purpose: Nowcasting model for current quarter GDP estimates
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- Updates: Multiple times weekly as new economic data releases
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- Useful for: Tracking economic activity between official BEA releases
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## Alternative Data Aggregators
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### International Sources
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**World Bank:**
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- Website: https://data.worldbank.org/indicator/NY.GDP.MKTP.CD?locations=US
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- API: https://datahelpdesk.worldbank.org/knowledgebase/articles/889392-about-the-indicators-api-documentation
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- Note: Sources U.S. GDP from BEA; use BEA/FRED directly for most accurate data
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**IMF (International Monetary Fund):**
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- Website: https://www.imf.org/en/Data
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- Note: Not recommended as primary GDP source; better for financial variables
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**OECD:**
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- Website: https://data.oecd.org/gdp/gross-domestic-product-gdp.htm
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- Note: Sources from BEA; use BEA/FRED directly for most accurate data
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## Data Download Methods Comparison
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| Source | Format | Authentication | Historical Coverage | Update Frequency | Best For |
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|--------|--------|----------------|---------------------|------------------|----------|
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| FRED CSV | CSV | None | 1947 (Q), 1929 (A) | Quarterly | Quick downloads, scripting |
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| FRED API | JSON/XML | API Key (free) | 1947 (Q), 1929 (A) | Quarterly | Automated data pipelines |
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| BEA iTable | CSV/Excel | None | 1929+ | Quarterly | Interactive exploration |
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| BEA API | JSON/XML | API Key (free) | 1929+ | Quarterly | Detailed NIPA table access |
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| MeasuringWorth | CSV | None | 1790+ | Annual updates | Long-term historical analysis |
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## Update Schedule
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### BEA Release Schedule (Three-Stage Process)
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Each quarter of GDP data goes through three releases:
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1. **Advance Estimate**: ~30 days after quarter end (8:30 AM ET)
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2. **Second Estimate**: ~60 days after quarter end (8:30 AM ET)
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3. **Third Estimate**: ~90 days after quarter end (8:30 AM ET)
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**Annual Comprehensive Update:**
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- Released each September
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- Revises 5+ years of historical data
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- Incorporates methodological improvements
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**Example Schedule for Q3 2025:**
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- Advance: October 30, 2025
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- Second: November 26, 2025
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- Third: December 23, 2025
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**2025 Release Calendar:**
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- Q4 2024 Third: January 30, 2025 ✅
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- Q1 2025 Third: June 26, 2025 ✅
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- Q2 2025 Third: September 25, 2025 ✅
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- Annual Update: September 25, 2025 ✅
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- Q3 2025 Advance: October 30, 2025 (upcoming)
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## How to Update This Dataset
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### Manual Update via FRED
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```bash
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# Download latest quarterly data
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curl -L "https://fred.stlouisfed.org/graph/fredgraph.csv?id=GDPC1" -o Real-GDP-Quarterly-1947-2025.csv
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# Download latest annual data
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curl -L "https://fred.stlouisfed.org/graph/fredgraph.csv?id=GDPCA" -o Real-GDP-Annual-1929-2024.csv
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# Verify download
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head -5 Real-GDP-Quarterly-1947-2025.csv
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tail -5 Real-GDP-Quarterly-1947-2025.csv
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```
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### Automated Update Script
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```bash
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#!/bin/bash
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# update-gdp-data.sh
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DATA_DIR="./Data/US-GDP"
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FRED_BASE="https://fred.stlouisfed.org/graph/fredgraph.csv"
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# Download quarterly real GDP
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curl -L "${FRED_BASE}?id=GDPC1" -o "${DATA_DIR}/Real-GDP-Quarterly-1947-2025.csv"
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# Download annual real GDP
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curl -L "${FRED_BASE}?id=GDPCA" -o "${DATA_DIR}/Real-GDP-Annual-1929-2024.csv"
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echo "GDP data updated: $(date)"
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```
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### Best Practices for Updates
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1. **Update after BEA's third estimate** (most complete data for the quarter)
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2. **Update after September annual revision** (historical data corrections)
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3. **Verify data integrity** after download (check first/last rows, row count)
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4. **Document updates** in UPDATES.md with date and data range
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5. **Note any methodology changes** from BEA annual updates
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## Data Verification
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### Quick Verification Checklist
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```bash
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# Check quarterly data
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wc -l Real-GDP-Quarterly-1947-2025.csv # Should be ~315 lines (header + 314 quarters)
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head -3 Real-GDP-Quarterly-1947-2025.csv # Should start with 1947-01-01
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tail -3 Real-GDP-Quarterly-1947-2025.csv # Should end with latest quarter
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# Check annual data
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wc -l Real-GDP-Annual-1929-2024.csv # Should be ~97 lines (header + 96 years)
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head -3 Real-GDP-Annual-1929-2024.csv # Should start with 1929-01-01
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tail -3 Real-GDP-Annual-1929-2024.csv # Should end with 2024-01-01
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```
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### Cross-Validation
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- Compare latest values with BEA news releases
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- Verify against FRED website display
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- Check that growth rates match reported economic news
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- Confirm no missing data points in series
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## Additional Research Resources
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### Economic Analysis
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- **NBER Business Cycle Dating**: https://www.nber.org/research/data/us-business-cycle-expansions-and-contractions
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- **BEA Methodologies**: https://www.bea.gov/resources/methodologies
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- **FRED Blog**: https://fredblog.stlouisfed.org/ (GDP analysis and interpretation)
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### Academic Papers
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- **BEA GDP Methodology**: https://www.bea.gov/resources/methodologies/nipa-handbook
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- **Historical GDP Construction**: Johnston & Williamson papers on MeasuringWorth
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### News & Analysis
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- **BEA News Releases**: https://www.bea.gov/news/current-releases
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- **Federal Reserve Economic Commentary**: District Fed banks publish GDP analysis
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- **Economic Calendar**: https://www.bea.gov/news/schedule
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## Support & Documentation
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### FRED Support
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- Email: stlsFRED@stls.frb.org
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- FAQ: https://fred.stlouisfed.org/docs/api/fred/
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### BEA Support
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- Contact Form: https://www.bea.gov/contact
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- Phone: (301) 278-9004
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- Email: customerservice@bea.gov
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---
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**Last Updated**: 2025-10-16
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**Next Recommended Check**: After Q3 2025 third estimate (late January 2026)
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