I recently had a client ask me what his farm might have been worth… in July, 1990. In Illinois, and many other states, getting current land sales data is not that difficult – simply check the courthouse. However, trying to find comparable sales from 21 years ago can be a challenge. Few lenders or courthouses retain this old of information, or if you can find it, it might be cost prohibitive.
Fortunately, the University of Illinois has developed a system (Index Numbers of Illinois Farmland Values) that landowners can use as a guide. Using USDA information, the formula utilizes a base index number from 1979 (100) and then adds or subtracts from the base each year to reflect whether land prices have gone up or down. Is this system 100% accurate? Probably not… the index is an average for the entire state and not for a specific county or township, and it doesn’t factor in what improvements may have been, or are currently, on the parcel. But many attorneys and other professionals find this methodology unbiased and in the absence of any other hard data, they can utilize the system to help determine the value of a property from years ago.
I would suggest using this index cautiously, especially if comparable sale information is available to use. But if lacking good comps, this formula may be quite helpful in determining historic land valuations.