Gerri: I am sorry for the delay, there is a problem with the "Ask Extension" message board and we did not know that my reply to you was not posted. Back to your question, the Illinois Dept. of Agriculture Domestic Marketing page (http://agr.state.il.us/marketing/domestic.html)
has links where you can download the application for the Centennial Farms Program. To qualify for Centennial Farm status, an agricultural property must have been owned by the same family of lineal or collateral descendants for at least 100 years. A lineal descendant is a person in the direct line of descent, such as a child or a grandchild. A collateral descendent is not a direct descendent, but is otherwise closely related, such as a brother, sister, uncle, aunt, nephew, niece or cousin. In addition, third party verification of your lineal claim must be submitted, such as an abstract researcher, title attorney, etc. This is all explained on the application forms and the form for the third party verification is included. There is an $18 application fee.