Probably the single most useful published collection of statistical information on virtually all aspects of life in the United States. And it usually directs you to the originally-published sources of data for more in-depth coverage. Earlier editions also are available online from the Census Bureau. Printed copies (1878-2011) are available in the library's Reference collection.
1 million statistics from over 18,000 sources (including both national and international data) ranging from agriculture to media & marketing and consumer & demographic data; also includes company dossiers and Industry Reports
Contains references to tens of thousands of data sources from the U.S. Federal Government, U.S. state governments, international intergovernmental organizations, and private sector groups, such as trade and professional associations.
U.S. Federal Government
These are tools for finding information from the Congress and Executive agencies of the U.S. Federal Government.
This is almost certainly the most comprehensive database of Congressional publications, some dating back as far as the late 1700's. Includes the complete texts of hearings and most other documents. An interesting sub-set of the database provides legislative histories. (Law Library subscription.)
Preeminent source of free data in several areas -- population, business and economics, income and poverty, housing, voting registration, and much more. Good starting points include the "Browse by Topic" and "Explore Data" tabs.
U. S. Supreme Court -- Texts of Decisions and Opinions