Your county board should be able to assist you with actual documentation showing when it was done or perhaps your counties public works dept can show you when it was made into a county road , BTW food for thought, but it would take a lot of research and homework on your part but if indeed this road was made into county road and you have your property surveyed to show how the road is situated compared to your boundries and if the road is entirely with in your land then couple things to think about, do you want to carefully review your counties records so you can determine if it was to be maintained by them did you pay taxes that went for maint of that road (search for your counties definition of min maint roads where they basically do nothing then see if this road is one of them) there has to be something in the county budget records that spells out its cost per X to maintain roads according to road classifications and some one should be able to provide you a very detailed break down of how your property taxes were used and if you paid for maint of the road or not. (if you paid for maint of the road and no maint was done then you will have to figure out is it worth taking legal action against your county to get a partial refund or a temporary reduction out of them as well as your learning via past records what the county paid for land taken from land owners for county roads so you can figure out if they had routinely paid in the past then to include a settlement from them.