Legislative Branch (Congress) Primary Sources
You'll want to turn your attention to Article I, which establishes the form and structure of the legislative branch of government.
Named after Thomas Jefferson, THOMAS is the Library of Congress's incredibly useful point of access to all the primary-source info you could possibly desire regarding legislative branch activity. Bills and resolutions, roll call votes, past laws, current schedules, and the Congressional Record—it's all here, in easily searchable form.
This landmark 1819 Supreme Court case interpreted the "Necessary and Proper Clause" of the Constitution in a liberal manner, establishing a precedent that would help lead to the gradual expansion of the implied powers of government over the course of the next two centuries.
The Missouri Compromise, passed in 1820, was one of the most important pieces of legislation passed by Congress in the first half of the nineteenth century. The compromise quieted sectional controversy between the slave South and free North for a generation.
In 1862, Congress passed a landmark bill providing funding for the construction of a transcontinental railroad. That railroad, completed in 1869, tied the West Coast to the East and helped initiate a period of rapid economic and industrial growth in the United States.
In 1887, Congress passed an act authorizing the federal regulation of the railroad industry, beginning a new era of extensive government regulation of the economy.
Perhaps the most important legislative accomplishment of the New Deal, the Social Security Act passed by Congress in 1935 established a new system of government-funded retirement insurance for all Americans.
In 1964, Congress ended a century of legal discrimination against blacks by passing the Civil Rights Act, which outlawed the Jim Crow system of de jure segregation.