As technology improved, other companies were added to the utilities subject to assessment. The returns include a notarized affidavit by a company official swearing to the accuracy of the accompanying property schedules. This began as a very detailed listing and description of individual pieces of property owned. Property listings became less individual and more categorical over the years. Franchise taxes were assessed as a property tax from 1896 until 1931 when intangible property was exempted from ad valorem assessment.
Mileage is specified either as tables or route maps.
A recapitulation form summarizes the total values of the miles and property for each county or taxing district in which the company operates. Copies of correspondence pertaining to the returns are often stapled to the company's returns, and the Tax Commission often made pencilled amended calculations on the forms. The volumes are arranged chronologically, thereunder alphabetically by title. Internally, most volumes are further arranged alphabetically by company. Public Utility Co's.