Nye County is a doozy. Aside from the enormous peak count -- it contains nearly a third as many ranked peaks as the entire state of CO -- there would be serious access issues for anyone with less pull than, say, an Air Force general. Much of the county is occupied by the Nellis Test Range and the Nevada Test Site (where nuclear weapons were tested and nuclear waste is stored). Part of Area 51 is in the county. Per LOJ, the county's leading peakbagger has completed barely 5% of its peaks.
https://upload.wikimedia.org/wikipedia/ ... map_en.pngNye seems like a strong candidate for the hardest county to finish in the contiguous 48 states. San Juan in Utah and Whatcom in Washington also come to mind though no doubt cases could be made for others with some combination of high peak count, technical difficulty, access restrictions, remoteness and/or tracklessness.