US Census Bureau

• American Community Survey (ACS) Data
• Census Data — 2020 Census Data, APIs, Data Tools, etc.
• Interactive Maps using Census Data
• Commuting Data (former Journey to Work) via US Census

US Department of Transportation, National Transportation Library

• Bureau of Transportation Statistics: A-Z Index
• Bureau of Transportation Statistics: Vehicle Inventory and Use Survey (VIUS) — Recently updated with 2021 survey results.
• Statistical Products and Data
• Repository and Open Science Access Portal: National Transportation Data Archive
• Freight Data Dictionary
• Research Data Management Resource Guide

US Department of Transportation, Federal Transit Administration

• National Transit Database (NTD)
• NTD Annual Data Publications Guide
• NTD Annual National Transit Summaries and Trends
• NTD Census Updates
• NTD Glossary

The National Academies of Sciences, Engineering, and Medicine, Transportation Review Board

South Coast Air Quality Monitoring District (South Coast AQMD)

• South Coast AQMD GIS Open Data Portal
• Air Quality (AQ) Details — Historical Data

Southern California Association of Governments (SCAG)

• SCAG Data Tools
• SCAG ArcGIS Open Data

Texas A&M Transportation Institute: Mobility Division

• National Congestion Data
• Additional Data and Trends