The C.P. Wahmann collection consists of official documents collected by Wahmann in the course of his administrative duties with Amtrak, and most deal directly with Amtrak operations or those of the commuter authorities whose trains run over Amtrak rails, although there are a few documents from the railroads that owned Amtrak properties prior to 1971.

Amtrak documents include track and interlocking diagrams showing changes and improvements made on the Boston-Washington Northeast Corridor between 1980 and 1994, as well as on the Philadelphia-Harrisburg "Keystone Corridor," the former Michigan Central Railroad main line running west from Detroit, and the extension of Amtrak operations beyond Boston to Portland, Maine. There are also employee handbooks and labor agreements for different classes of train service and maintenance of way employees, crew assignment lists, manuals for locomotives and cars, employee timetables and operating rules, manuscript versions of public timetables, and train consist books. There are special reports on the early version of proposals to build a new Penn Station in the James A. Farley Post Office, for the rehabilitation of 30th Street Station, and a track plan of Grand Central Terminal in New York. There is a memorandum on the wreck of the Colonial at Chase, Maryland, which led to the removal of most Conrail freight trains from the Northeast Corridor, and a National Transportation Safety Board report on the wreck of the Night Owl at Chester, Pennsylvania, in 1988.

Other materials unrelated to Amtrak include primarily timetables, track maps, and rulebooks for commuter authorities at Boston, Greater New York, Philadelphia, Baltimore, Washington and Chicago operating over Amtrak rails or in connection with Amtrak facilities.