In the United States, the word “treaty” is reserved for an agreement that is made “by and with the Advice and Consent of the Senate” (Article II, section 2, clause 2 of the Constitution). When the Senate considers a treaty, it may approve it as written, approve it with conditions, reject and return it, or prevent its entry into force by withholding approval. The Senate historically has given its unconditional advice and consent to the vast majority of treaties submitted to it.
International agreements not submitted to the Senate are known as “executive agreements” in the United States, but they are considered treaties and therefore binding under international law. For a lengthy discussion and history of the Senate’s role in treaties and international agreements, see Treaties and Other International Agreements: The Role of the United States Senate.
You can research the status of treaties submitted to the U.S. Senate on Congress.gov. This database provides information from the 94th Congress (1975-1976) to the present. Treaties that were submitted prior to 1975 and were still pending at the start of the 94th Congress are included.
Links to the full text of treaties submitted to the U.S. Senate from 1995 to the present are available on the Government Publishing Office (GPO) website.
The U.S. Department of State publishes Treaties in Force, an annual listing of bilateral and multilateral treaties and other international agreements to which the United States is a party. This publication is available electronically and may also be available in local public and college libraries. In addition, the State Department provides the full text of many treaties through the Office o Treaty Affairs.
The Department of State publishes the United States Treaties and Other International Agreements series. TIAS “slips” are cumulated annually in United States Treaties and Other International Agreements. Published since 1950, these volumes serve as a compilation of treaties and agreements the United States has been party to in years past. Before 1950, the texts of treaties and other international agreements were printed in United States Statutes at Large.
All of these publications may be available in large public library systems, and college libraries, frequently as a part of their participation in the Federal Depository Library Program (FDLP). Over 1,100 libraries participate in the FDLP, collecting and/or providing public access to government documents. A list of depository libraries is available on GPO’s website. Most depository libraries are within a university or state library, so calling ahead to ask about hours is advised.