Good history, Handy. The numbering reflected the number of registered vehicles in a county in 1922. Seeing the changes over the next hundred years in the counties is fascinating (well, if you're a Nebraska history nerd like me). While most of the top 10 have stayed roughly the same, there are some outliers. Custer County (Broken Bow) is #4. Gage County (Beatrice), #3, would be double digits now. Saunders County (Wahoo) at #6 would slip. Knox County (Creighton, but County seat is Center) would move way down the list from #12. Many would move up the list, but most prominently Sarpy County as mentioned.