The record of forms and in most cases map sketches on which local postmasters supplied data to the Topographer of the U.S. Post Office Department for use in determining post office site locations relative to nearby post offices, transportation routes and facilities. There is not an exact standardization of all reports. Earlier reports may not be as detailed as those of a later date and in some cases there may be correspondence queries of postmasters for more complete information. As well as an alphabetical arrangement by state or territory, there is also an alphabetical arrangement within a state, such as West Virginia, by county. There is an imperfect alphabetical arrangement of site locations at the county level with site location name changes not noted. In instances of more than one report for a particular site, generally a backward chronological order is followed from the most recent report to that of the earliest. With few exceptions the reports do not show exact site locations, nor do they include building survey information of the post offices. The reports were used by the Topographer to prepare postal maps for use by the department and for sale to the public. In themselves, the reports constituted an important part of the procedure for establishing new post offices.

Included in the title of each reel is the number assigned to the original microfilm reel by the Library of Congress.