Large and small format daybook type dairies that document the ongoing activities of Clark as he progressed in his career. Covering the period from his first association with the Highlander Center of New Market, Tennessee through his tenure as the interim director of Greenpeace US, these volumes contain brief notations of meetings, "to-do" lists, contact information, thoughts, and travel itineraries. Much of the content appears to be randomly assembled, and while an attempt has been made to put the volumes into strict chronological order it is not always possible. Clark sometimes recycled journals with unused pages so the chronology is mixed up. The dates listed for each volume represent the earliest and last verified dates written within, and the possibility that notations precede or follow those dates in any given volume should be understood. Volumes 1-50 are larger format, while volumes 51 through 86 are smaller, pocket memoranda book size. These items have been arranged in general chronological order.

During his lengthy career, Clark wrote numerous essays on topics which concerned him, and delivered addresses to various groups that he led, or had been invited to speak to. This series presents a collection of these essays and speeches, along with articles written about Clark and his activities, and arranged in alphabetical order. Other essays and reports pertaining to specific organizations can be found in the appropriate series.

Highlander is a school for activist dealing with civil rights, labor, anti-poverty and human rights concerns and environmental issues throughout Appalachia and the American south. Over its first forty years, Highlander was the most controversial school for adults in the southern United States because of its work with labor unions and civil rights groups. In 1972, Clark became president of the school and oversaw major programmatic transitions, shifting from work primarily with black activists into work with white Appalachians in order to create a national multi-racial coalition of poor people. These files represent materials created or collected by Mike Clark during his time with the Center, including those travel materials he gathered while visiting Europe in 1970 while working for the Center. They have been alphabetically arranged.

The Northern Lights Research and Education Institute, Inc. of Helena, Montana was a regional research center operating in Montana, Idaho and Wyoming. It was an effort on the part of regional environmental community members to create a progressive think-tank that would investigate natural resource issues in the Northern Rockies and create a means of more effectively engaging the public in natural resources debates. In 1982, Mike Clark became the founding executive director and established the first office and programs in Helena, staying with the organization until 1984. The Institute eventually moved its offices to Missoula before it officially closed on May 2, 2003. Among the work conducted by the organization was the publication of a series of oral history interviews (mostly conducted by Deborah Tuck) of western community leaders. These interviews were published in a 1986 book titled . Book edited by Tom Bethell. These boxes contain oral history transcripts and the edited versions published in the book.

In the late 1980s, a proposed gold mine on the Northeast corner of Yellowstone National Park became a poster child for national efforts to reform the 1872 Hard Rock Mining law. Located near Cooke City, Montana, in the New World Mining District, the site became the center of a mining effort by the Noranda Corporation, a Canadian company, through its subsidiary arms, Hemlo Gold Company and Crown Butte Resources, Ltd. Concerned local citizens formed the Beartooth Alliance, an arm of the Northern Plains Resource Council, and began to monitor the mine exploration. Ralph and Sue Glidden and Heidi and Jim Barrett, and Wade King were key leaders. Julia Page and Richard Parks of the Gardiner-based Bear Creek Council provided strategic support. Eventually the groups decided to oppose the mine and were joined by other NGOs, including the Greater Yellowstone Coalition, American Rivers, the Sierra Club, Montana Wildlife Federation, Wyoming Outdoor Council, Gallatin Wildlife Association, and the Northwest Wyoming Resource Council. Key players in the ten-year campaign included a wide range of citizens. GYC board members helped with fund raising and outreach around the country, including Dwight Minton, Albert Wells, Tim Swanson, Gretchen Long Glickman, John Winsor and Andy Andrews. Local ranch owners Gus Hart and Ed Spencer broaded the effort. Doug Honnold, the head of the Northern Rockies office of Earthjustice, was the lead attorney for the conservation community and was assisted by attorney Susan Daggett. Tom Cassidy of American Rivers was a key resource. GYC staffers Ed Lewis, Louisa Willcox, Bob Ekey, Peter Angst, Don Bockman and Brian Kuehl provided crucial campaign support. On the company side, Noranda officials Ian Bayer, Joe Baylis and former Senator Birch Bayh were crucial decision-makers. After Earthjustice won a lawsuit determining that Noranda had violated key provisions of the federal Clean Water Act, Honnold and Clark led negotiations with the company and the federal government. Then-President Bill Clinton's staff and Clark and Honnold spent months working with the company until a final agreement was reached. The federal administration then withdrew all mining permits and closed the New World Mine District to further mining claims. Clinton announced this victory on August 12, 1996. Officials with the President's Council of Environmental Quality led the federal effort, particularly CEQ senior staffer Ray Clark and CEQ Chair Katie McGinty. Yellowstone Park Superintendent Mike Finley was instrumental in the successful effort to halt the mine.

The files in this series represent documentation kept by Mike Clark during the long battle, including personal notes, reports, environmental impact statements, legal documents and correspondence. The complete documentation of the ten-year campaign to stop the mine can be found in the records of the Greater Yellowstone Coalition and the offices of Earthjustice, in Bozeman. Many of the groups and individuals mentioned above show up in these files. The folders in this series have retained the labels Clark assigned them with minor revisions for consistency and have been placed in alphabetical order. Folders containing critical letters and memos regarding the negotiations have been indicated with an asterisk.

Within this set of documents are the papers, notes, and workings of Mike Clark and colleagues culminating in the Yellowstone Heritage Trust's Land Ownership and Ranchland Dynamics Study. Julia Haggerty was the primary researcher. Her colleague Professor Hannah Goshell explains this study in a grant proposal, also contained in this file, describing, "look[ing] at large ranch sales in three Rocky Mountain Counties over the past ten years and consider[ing] some of the implications." Examining socioeconomic, farming/ranching, types of ownership, and public use, the researchers express the importance of land conservation and private land ownership without coercive buy-out tactics. As Clark puts it, conservation efforts "require comprehensive information on ranchland ownership dynamics" in order to develop "strategies for private land conservation throughout Northern Rocky Mountain Region" to avoid fragmentation of landscapes in "critical areas." With comprehensive budgets, correspondence, grant proposals, research, and drafts, this file creates a narrative of Ranchland Dynamics.

Glacier National Park is one of the premiere national parks in the lower 48 states, spanning over a million acres of land throughout Canada, Montana and Idaho. The park contains one of the most complete North American ecosystem on the continent, not having a recorded an extinction in over 200 years. This pristine region earned the nickname "Crown of the Continent" from 20th Century conservationist George Grinnell. On-going efforts to protect it involve government agencies and NGO's on both sides of the border. The National Parks Conservation Association hired Clark as a consultant to interview leaders of these groups to determine if a new regional coordinating group should be created. Clark worked as a consultant and organizer for the group: conducting interviews, assessing protocols, gathering research, and connecting with a multitude of groups within the "Crown". These files are the collection of information, research, correspondence, and reports he gathered while working on the project.

This series consists of material gathered or created by Mike Clark on a variety of topics he was interested in, along with a few documenting his time with the Greater Yellowstone Coalition, the Environmental Policy Institute, and Greenpeace US. The subject matter is broadly diffuse, with some files clearly the result of organizational work and others providing background information for policy statements and essays. Of particular interest is a folder of information Clark gathered on a notorious labor incident in 1922 Herrin, Illinois from records at the headquarters of the United Mine Workers. The folders have been alphabetically arranged.

A collection of visual materials from the Clark collection, including VHS tapes, photo albums, loose photos and certificates. The photograph album was a gift from the staff of the GYC on Clark's retirement as director of the organization, and many of the loose numbered photographs document the ceremony attended by President Bill Clinton to recognize the withdrawal of the New World Mining District from development.