The folders of correspondence contain both incoming and outgoing letters and are arranged by month. They consist chiefly of invitations to attend meetings and civic events, send delegates to meetings of professional organizations, or to speak to local organizations and at banquets; a few letters acknowledge the receipt of appointments made by the governor. Copies of Governor Clark's replies to invitations are usually included with the original incoming letter.

Organizations are listed in the corresponding folder where they should be found, rather than the exact date of sending or receipt. Invitations from governors of numerous states and Canadian provinces, mayors of Idaho and surrounding state's towns, presidents and officials of Idaho educational institutions, Idaho state senators and other elected officials can also be found in the Correspondence folders.

Printed invitations to which replies have been attached are included in the following list; printed invitations to which there are no replies are in a separate folder and are therefore listed separately.