US statutory law consists of the laws passed by the legislature.
    For the federal government, it is the acts passed by the United States Congress. [For a more information on how this is done, see Learn About the Legislative Process].  For states, it is the acts passed by their individual legislatures.

There are two kinds of acts:

1.  Public laws relate to the general public
2.  Private laws relate to specific institutions or individuals.

Regulatory, or administrative, law comes from the Executive Branch and its agencies, and independent regulatory agencies.
Agencies are given the authority to create administrative law through laws enacted by Congress and state legislatures. The law comes in the form of rules, regulations, procedures, orders, and decisions.
Agencies act in two roles:

1. in a legislative-like capacity when promulgating rules and regulations;
2. and in a judicial-like capacity when conducting hearings and issuing rulings and decisions on particular matters.

On the federal level, the process of administrative agency rule-making (from the initial notice to the promulgation of a final rule) is documented in two main titles of the Federal Register publication system: the Federal Register and the Code of Federal Regulations.
State agency rule-making follows the same process (check by individual states).

Code of Federal Regulations - CFR

• Administrative rules passed by agencies
  • codification of the permanent rules and regulations published in the Federal Register
• subject access to regulations
• Regulations.gov
  • make and find comments

• Nexis Uni and GovInfo

Federal Register

• New and amended regulations
  • summary, explanatory and documentary information about the regulation
  • this can be of great importance in determining the meaning and application of a final rule and regulation
• Access via :
  • Nexis Uni
  • GovInfo (1996-on)   
  • List of Sections Affected
    • Use the List of Sections Affected to Update the CFR

Other

• Executive Orders via the Federal Register (1994-)
  • Historic via Library of Congress
• Federal Agency Decisions (via Nexis Uni)
• Executive Agencies  (list of links from FindLaw)