Who tracks the largest cottonwood trees inIowa, specifically Cedar co is where i live. I have a really huge one on mt acreage.
Cedar County Iowa
At one time, the Iowa Department of Natural Resources (Forestry division) maintained a list of the champion trees of Iowa. I suggest contacting your DNR district forester. A list of the Iowa district foresters can be found at https://www.iowadnr.gov/Conservation/Forestry/Forestry-Landowner-Assistance