The Joint Committee on Taxation has issued Historical Development And Present Law Of The Federal Tax Exemption For Charities And Other Tax-Exempt Organizations (JCX-29-05) (248 pages).  Here is the Introduction:

This document . . . provides a description of the historical development and present law of the Federal tax exemption for charities and other tax-exempt organizations. This document begins with an executive summary. Following the executive summary, Part I of this document provides an overview of organizations exempt from Federal income tax, including statistical information about the sector, reasons for tax exemption, and common tax law features of exempt organizations. Part II describes the history and evolution of the exempt status of organizations described in § 501(c)(3), including a discussion of the meaning of exempt purposes described in § 501(c)(3), the distinction between private foundations and public charities, a general history of the unrelated business income tax, and an overview of related organization structures used by exempt organizations. Part III contains a description of several types of organizations that are described in § 501(c)(3), including a discussion of the change in legal standards over time. Organizations described here are hospitals, elder care facilities, credit counseling organizations, low-income housing organizations, environmental organizations, and college sports organizations. Part IV provides statistical information showing the size and growth of the charitable and exempt sectors. Part V is an overview of tax and nontax benefits of exemption for § 501(c)(3) organizations and a summary of a Congressional Research Service document (included as an Appendix to this pamphlet) that lists the benefits of charitable exemption under Federal and certain State laws. Part VI is a description, including the legislative history, of the many various organizations that may qualify for tax-exempt status.