The American Public Transportation Association records consist of material pertaining to the activities of APTA as well as both the American Transit Association (ATA) and the Institute for Rapid Transit (IRT). Types of materials in the collection include: memoranda, correspondence, reports, legislative information, industry-related information (such as brochures and technical reports), and membership information.

Series 1: Committees includes correspondence, meeting minutes, and reports created by various committees as well as some subcommittees in APTA and ATA. The composition of the committees typically included association staff and transit system managers. The committees largely worked on issues related to equipment and finances with a smaller number devoted to legislation, marketing, and labor issues. The committees and subcommittees overlap to some extent due to changes in the structure of the association and as a result of changes in transit priorities. The folders date back to the 1908 and the American Electric Railway Transportation and Traffic Association, a precursor to ATA, but many of the folders consist of committee work from the 1970s.

Series 2: Meetings and Publications includes organizational documents such as the constitution, by-laws, annual reports, and press releases. There is also correspondence and information on industry group meetings attended by APTA officials. Officials attended local, national, and international conferences on planning, equipment, and management. There are also files on meetings held by groups with APTA, such as the Rail Transit Group. The organizational documents date from the 1920s, but many of the meeting files are from the 1960s and 1970s.

Series 3: Equipment, Finances, and Statistics is the largest series and consists of a wide range of topics on technical and financial issues. The documents on equipment cover the various vehicles used by transit systems including streetcars, trolley coaches, motor buses, and trains. In particular there are a large number of files on the testing and technical specifications about the Urban Rapid Rail Vehicle and Systems Program Advanced Concept Train, a joint project undertaken in the late 1970s by both APTA and the U.S. Department of Transportation. The financial and statistical files overlap to some extent since there are many files on subjects such as fares and accident claims. Other statistical files consist of data on route configurations and responses to questionnaires on a variety of topics, such as the use of tires. Also found in this series are files on specific advisory and technology and advisory boards that existed within APTA. The files in this series largely date from the 1940s through the 1980s.

Series 4: Legislation contains files on legislation, primarily federal, that impacted the transit industry. Many of files focus on the attempts by Congress to pass legislation in the 1970s to provide large-scale funding for transit by using revenue from the Highway Trust Fund, which was established in 1956 to finance the construction of the national interstate system. Documents include correspondence, congressional testimonies, drafts of bills, and reports. There are also several folders that document efforts to fund transit at the state level.

Series 5: Labor consists of reports, correspondence, and legislation on various labor and employment subjects. In particular there are a large number of files on 13(c), a section of the Urban Mass Transportation Act that allowed unions to dispute federal funding for transit systems if they believed that workers would be adversely affected. Another large group of documents found in this series are annual reports on wages and working conditions compiled from information sent in by transit system managers. There are also some files on hiring practices and training. The files largely date from the 1940s to the 1970s.

Series 6: Local Transit consists of files on transit systems in cities and states in the U.S. as well as some files on international cities. The files mostly consist of clippings sent in by transit system managers, but there are also maps, pamphlets, reports, and other documents in many of the folders. There is some overlap between the folders with city titles and the folders with state titles. For instance, there may be some files on Boston found in the "Massachusetts" folder, but in general the folders with the city titles contain the bulk of the information on the transit systems in those particular cities. For the most part, the clippings document the problems faced by the private transit companies following World War II, and some of the folders contain charts and tables on the transit company failures all across the United States.

Series 7: Oversize contains some issues of the APTA publication Passenger Transport, and there are also two reports: one on the Chicago Transit Authority and another one a planning project in Honolulu, Hawaii.