Published annually 1878-2012, scanned copies are provided by the Census Bureau.

2013-present editions from ProQuest (NU Affiliated users only)

Established in 1958, the Transportation Library at Northwestern University contains over 500,000 items. As one of the largest transportation information centers in the world, the Transportation Library collects information on all transportation modalities including: air, rail, highway, pipeline, water, urban transport and logistics. It includes a significant collection on law enforcement, police management and traffic enforcement. Its collection of environmental impact statements is one of the most complete in the world.