Prairie Fires were reported in Monthly Weather Review on a regular basis during the late 1800s. The location, dates and durations of the fires were reported. Sometimes the extent of the fire was also noted.
Fire Report from Monthly Weather Review [January, 1879] Prairie Fires at North Platte, Neb. (24th-26th); Independence, Iowa. (29th); Fort Sill, Ind. (22nd); Eagle Pass, Texas (15th & 16th), etc., etc.
Now I am not a specialist on prairie fires but perhaps the Monthly Weather Review reports are the only national record of prairie fires to be had. As this might be of value to our prairie-LTER friends I pass it on for what it is worth.